Reduced density hollow glass microsphere polymer composite

ABSTRACT

The invention relates to a hollow glass microsphere and polymer composite having enhanced viscoelastic and rheological properties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of application Ser. No. 14/965,997,filed Dec. 11, 2015, which is a continuation of application Ser. No.12/769,553, filed Apr. 28, 2010 now U.S. Pat. No. 9,249,283, andProvisional Application No. 61/173,791, filed Apr. 29, 2009.

FIELD OF THE INVENTION

The invention relates to a composite of a hollow glass microsphere and apolymer with modifiable properties to produce enhanced products. Thenovel properties are produced in the composite by novel interactions ofthe components. The hollow glass microsphere and polymer compositematerials are a unique combination of a hollow glass microspheretypically particulate components and a polymer material that optimizesthe composite structure and characteristics through blending thecombined polymer and hollow glass micros to 90% of the base polymermaterials to achieve true composite properties.

BACKGROUND OF THE INVENTION

Substantial attention has been paid to the creation of compositematerials with unique properties. Included in this class of materialsare materials with improved viscoelastic character, varying densities,varying surface characteristics and other properties which may be usedto construct a material with improved properties.

Composite materials have been made for many years by combining generallytwo dissimilar materials to obtain beneficial properties from both. Atrue composite is unique because the interaction of the materialsprovides the best properties and characteristics of both components.Many types of composite materials are known. Generally, the artrecognizes that combining metals of certain types and at proportionsthat form an alloy provides unique properties in metal/metal alloymaterials. Metal/ceramic composites have been made typically involvingcombining metal powder or fiber with clay materials that can be sinteredinto a metal/ceramic composite.

Combining typically a thermoplastic or thermosetting polymer phase witha reinforcing powder or fiber produces a range of filled materials and,under the correct conditions, can form a true polymer composite. Afilled polymer, with the additive as filler, cannot display compositeproperties. A filler material typically is comprised of inorganicmaterials that act as either pigments or extenders for the polymersystems. Fillers are often replacements for a more expensive componentin the composition. A vast variety of fiber-reinforced composites havebeen made typically to obtain fiber reinforcement properties to improvethe mechanical properties of the polymer in a specific composite.

Many of these materials containing polymer and particulate areadmixtures and are not true composites. Admixtures are relatively easilyseparable into the constituent parts and, once separated, display theindividual properties of the components. A true composite resistsseparation and displays enhanced properties of the input materialswhereas the individual input materials often do not display the enhancedproperties. A true composite does not display the properties of theindividual components but display the unique character of the composite.

While a substantial amount of work has been done regarding compositematerials generally, the use of inorganic, non metallic or mineralparticles in a polymer composite has not been obtained. Tuning thedensity the formation of these materials into a composite of a polymerand an inorganic mineral or non-metal provides novel mechanical andphysical properties into the composite and, when used, obtainsproperties that are not present in other materials. A need exists formaterial that has tunable density, low toxicity, and improved propertiesin terms of increased conformance, elasticity, and pliability.

BRIEF DESCRIPTION OF THE INVENTION

The invention relates to a composite of a hollow glass microsphere and apolymer having improved and novel properties methods of making andapplications of the materials. The material of the invention is providedthrough a selection of non metallic, hollow glass microsphere particlespecie, particle size (P_(s)) distribution, molecular weight, andviscoelastic character and processing conditions. The particles have aspecific and novel particle morphology that cooperates with thecomponents of the invention to provide the needed properties to thecomposite. The material attains adjustable chemical/physical propertiesthrough hollow glass microsphere selection and polymer selection. Theresulting composite materials exceed the contemporary composites interms of density, surface character, reduced toxicity, improvedmalleability, improved ductility, improved viscoelastic properties (suchas tensile modulus, storage modulus, elastic-plastic deformation andothers) electrical/magnetic properties, resistance to condition ofelectricity, vibration or sound, and machine molding properties. We havefound that density and polymer viscoelasticity measured as elongationare useful properties and useful predictive parameters of a composite inthis technology. In the production of useful enhanced properties, thepacking of the selected particle sizes (P_(s), P_(s) ¹, etc.),distribution population particles and the selection of the particulateor mixed non-metal, inorganic, ceramic or mineral particulate, willobtain the enhanced properties.

BRIEF DISCUSSION OF THE DRAWINGS

FIGS. 1 to 5 shows enhanced rheological properties in a sealant.

DETAILED DISCUSSION OF THE INVENTION

The invention relates to novel composites made by combining a hollowglass microsphere particulate with a polymer to achieve novel physicalelectrical surface and viscoelastic properties. A hollow glassmicrosphere particulate having a particle size ranging from about 10microns to about 1,500 microns can be used in the invention. The maximumsize is such that the particle size (P_(s)) of the particle is less than20% of either the least dimension or the thinnest part under stress inan end use article. Such particles can be substantially hollow andspherical.

Both thermoplastic and thermosetting resins can be used in theinvention. Such resins are discussed in more detail below. In the caseof thermoplastic resins, the composites are specifically formed byblending the particulate and interfacial modifier with thermoplastic andthen forming the material into a finished composite. Thermosettingcomposites are made by combining the particulate and interfacialmodifier with an uncured material and then curing the material into afinished composite.

In both cases, the particulate material is typically coated with aninterfacial surface chemical treatment that supports or enhancing thefinal properties of the composite.

A composite is more than a simple admixture. A composite is defined as acombination of two or more substances intermingled with variouspercentages of composition, in which each component results in acombination of separate materials, resulting in properties that are inaddition to or superior to those of its constituents. In a simpleadmixture the mixed material have little interaction and little propertyenhancement. One of the materials is chosen to increase stiffness,strength or density. Atoms and molecules can form bonds with other atomsor molecules using a number of mechanisms. Such bonding can occurbetween the electron cloud of an atom or molecular surfaces includingmolecular-molecular interactions, atom-molecular interactions andatom-atom interactions. Each bonding mechanism involves characteristicforces and dimensions between the atomic centers even in molecularinteractions. The important aspect of such bonding force is strength,the variation of bonding strength over distance and directionality. Themajor forces in such bonding include ionic bonding, covalent bonding andthe van der Waals' (VDW) types of bonding. Ionic radii and bonding occurin ionic species such as Na⁺Cl⁻, Li⁺F⁻. Such ionic species form ionicbonds between the atomic centers. Such bonding is substantial, oftensubstantially greater than 100 kJ-mol⁻¹ often greater than 250 kJ-mol⁻¹.Further, the interatomic distance for ionic radii tend to be small andon the order of 1-3 Å. Covalent bonding results from the overlap ofelectron clouds surrounding atoms forming a direct covalent bond betweenatomic centers. The covalent bond strengths are substantial, are roughlyequivalent to ionic bonding and tend to have somewhat smallerinteratomic distances.

The varied types of van der Waals' forces are different than covalentand ionic bonding. These van der Waals' forces tend to be forces betweenmolecules, not between atomic centers. The van der Waals' forces aretypically divided into three types of forces including dipole-dipoleforces, dispersion forces and hydrogen bonding. Dipole-dipole forces area van der Waals' force arising from temporary or permanent variations inthe amount or distribution of charge on a molecule.

TABLE 1 Summary of Chemical Forces and Interactions Strength Type ofInteraction Strength Bond Nature Proportional to: Covalent bond Verystrong Comparatively long r⁻¹ range Ionic bond Very strong Comparativelylong r⁻¹ range Ion-dipole Strong Short range r⁻² VDW Dipole-dipoleModerately Short range r⁻³ strong VDW Ion-induced Weak Very short ranger⁻⁴ dipole VDW Dipole- Very weak Extremely short r⁻⁶ induced dipolerange VDW London Very weak^(a) Extremely short r⁻⁶ dispersion forcesrange ^(a)Since VDW London forces increase with increasing size andthere is no limit to the size of molecules, these forces can becomerather large. In general, however, they are very weak.

Dipole structures arise by the separation of charges on a moleculecreating a generally or partially positive and a generally or partiallynegative opposite end. The forces arise from electrostatic interactionbetween the molecule negative and positive regions. Hydrogen bonding isa dipole-dipole interaction between a hydrogen atom and anelectronegative region in a molecule, typically comprising an oxygen,fluorine, nitrogen or other relatively electronegative (compared to H)site. These atoms attain a dipole negative charge attracting adipole-dipole interaction with a hydrogen atom having a positive charge.Dispersion force is the van der Waals' force existing betweensubstantially non-polar uncharged molecules. While this force occurs innon-polar molecules, the force arises from the movement of electronswithin the molecule. Because of the rapidity of motion within theelectron cloud, the non-polar molecule attains a small but meaningfulinstantaneous charge as electron movement causes a temporary change inthe polarization of the molecule. These minor fluctuations in chargeresult in the dispersion portion of the van der Waals' force.

Such VDW forces, because of the nature of the dipole or the fluctuatingpolarization of the molecule, tend to be low in bond strength, typically50 kJ mol⁻¹ or less. Further, the range at which the force becomesattractive is also substantially greater than ionic or covalent bondingand tends to be about 3-10 Å.

In the van der Waals composite materials of this invention, we havefound that the unique combination of particulate, the varying butcontrolled particle size of the particle component, the modification ofthe interaction between the particulate and the polymer, result in thecreation of a unique van der Waals' bonding. The van der Waals' forcesarise between particulate atoms/crystals in the particulate and arecreated by the combination of particle size, polymer and interfacialmodifiers in the composite.

In the past, materials that are characterized as “composite” have merelycomprised a polymer filled with particulate with little or no van derWaals' interaction between the particulate filler material. In theinvention, the interaction between the selection of particle sizedistribution and interfacially modified particle enables the particulateto achieve an intermolecular distance that creates a substantial van derWaals' bond strength. The prior art materials having little viscoelasticproperties, do not achieve a true composite structure. This leads us toconclude that this intermolecular distance is not attained in the priorart. In the discussion above, the term “molecule” can be used to relateto a particle, a particle comprising non-metal crystal or an amorphousaggregate, other molecular or atomic units or sub-units of non metal orinorganic mixtures. In the composites of the invention, the van derWaals' forces occur between collections of metal atoms that act as“molecules” in the form of mineral, inorganic, or non-metal atomaggregates.

The composite of the invention is characterized by a composite havingintermolecular forces between particles about 30 kJ-mol⁻¹ and a bonddimension of 3-10 Å. The particulate in the composite of the inventionhas a range of particle sizes such that about at least 5 wt.-% ofparticulate in the range of about 10 to 500 microns and about at least 5wt.-% of particulate in the range of about 10 to 250 microns, and apolymer, the composite having a van der Waals' dispersion bond strengthbetween molecules in adjacent particles of less than about 4 kJ-mol⁻¹and a bond dimension of 1.4 to 1.9 Å or less than about 2 kJ-mol⁻¹ andthe van der Waals' bond dimension is about 1.5 to 1.8 Å.

In a composite, the reinforcement is usually much stronger and stifferthan the matrix, and gives the composite its good properties. The matrixholds the reinforcements in an orderly high-density pattern. Because thereinforcements are usually discontinuous, the matrix also helps totransfer load among the reinforcements. Processing can aid in the mixingand filling of the reinforcement or particulate. To aid in the mixture,an interfacial modifier can help to overcome the forces that prevent thematrix from forming a substantially continuous phase of the composite.The composite properties arise from the intimate association obtained byuse of careful processing and manufacture. We believe an interfacialmodifier is an organic material that provides an exterior coating on theparticulate promoting the close association but no reactive bonding ofpolymer and particulate. Minimal amounts of the modifier can be usedincluding about 0.005 to 8 wt.-%, or about 0.02 to 3 wt. %. For thepurpose of this disclosure, the term “particulate” typically refers to amaterial made into a product having a distribution or range of particlesize. The size can be greater than 10 microns and having a particle sizedistribution containing at least some particulate in the size range of10 to 4000 microns. The particles have a range of sizes and circularityparameters. In a packed state, this particulate has an excluded volumeof about 13 to 61 vol.-% or about 30 to 75 vol.-%. Alternatively, theparticulate can have greater than about 30 vol. %, greater than about 40vol. % or about 40 to 70 vol.-% particle loading. In this invention, theparticulate can comprise two, three or more particulates sources, in ablend of materials of differing chemical and physical nature. Regardingthe particulate material, the term a “majority of the particulate”indicates that while the particulate can contain some small amount ofsmall fines and some particles that are large with respect to therecited range, the majority (greater than 95%, 90%, 85%, etc.) fallwithin the recited range and contribute to the physical properties ofthe composite. The glass can be combined with a second particulate suchthat the second particle differs from the glass by at least ±5 microns,or has a particle size such that according to the formula P_(S)≧2 P_(S)¹ or P_(S)≦0.5 P_(S) ¹ wherein P_(S) is the particle size of the hollowglass microsphere and P_(S) ¹ is the particle size of the particulate.

For the purpose of this disclosure, the term “non-metallic” relates to amaterial substantially free of a metal in an oxidation state,approximately 0.

For the purpose of this disclosure, the term “inorganic” relates to amaterial substantially free of carbon in the form or organic carbon orcovalently bonded carbon compounds. Accordingly, compounds such ascalcium carbonate or sodium bicarbonate are considered inorganicmaterials while most organic compounds including small molecules such asmethane, ethane, ethylene, propylene, related polymer species, etc., arecommonly considered organic materials.

A “mineral” is defined as an element or chemical compound that isnormally crystalline and that has been formed as a result of geologicalprocesses (Ernest H. Nickel, 1995, The definition of a mineral, TheCanadian Mineralogist, vol. 33, pp. 689-690). For the purpose of thisinvention, the term “non-metal, inorganic or mineral” (mineral) isdefined, as above, as an element or chemical compound that is normallycrystalline and that has been formed as a result of geologicalprocesses.

Particle Morphology Index

The interfacial modification technology depends on the ability toisolate the particles from that of the continuous polymer phase. Theisolation of the particulates requires placement of a continuousmolecular layer(s) of interfacial modifier to be distributed over thesurface of the particles. Once this layer is applied, the behavior atthe interface of the interfacial modifier to polymer dominates thephysical properties of the composite (e.g. tensile and elongationbehavior) while the bulk nature of the particle dominates the bulkmaterial characteristics of the composite (e.g. density, thermalconductivity, compressive strength). The correlation of particulate bulkproperties to that of the final composite is especially strong due tothe high volume percentage loadings of particulate phase associated withthe technology.

There are two key attributes of the particle surface that dictate theability to be successfully interfacially modified: 1) The overallsurface area of the particles on a large scale; large being defined asabout 100× or more compared to the molecular size of the interfacialmodifier. In the case of NZ-12, the molecular diameter is about 2260 μmand 2) Particle surface characteristics that are on the order of thesize of the interfacial modifier being applied.

The following particle morphology attributes specifically contribute tothe ability to effectively interfacially modify the particles. Combiningthe different particle attributes we have derived a particle morphologyindex. Discussion will reveal that vastly different particle types canbe effectively modified from large, smooth, round, and impervioussurface types (low particle morphology index) to small, rough, irregularand porous (high particle morphology index):

Particle Size (P_(s))

A wide range of particle sizes can be effectively interfaciallymodified. Successful modification has been completed with particles witha major dimension as small as −635 US mesh (<20 μm) to particles aslarge as −40US mesh (−425 μm). Undoubtedly, larger particle sizes can beeffectively modified (1,500 μm or greater). The absolute size of theparticle being modified is not important; the relative size of the majordimension of the largest particle to the minimum critical dimension ofthe end article is more important. Our composite experience guides usthat the major dimension of the largest particles should not be morethan ⅕^(th) of the minimum critical dimension of the end article. As theparticles become smaller the particulate surface area increases. Forsmooth spheres of a constant density, there is 28 times more surfacearea in spheres of 15 μm than 425 μm diameter within a given mass ofmaterial. There is 100 times the surface area for particles of 1,500 μmdiameter compared to 15 μm.

Dosage levels of interfacial modifier have been effectively adjusted tocompensate for changes in surface area due to particle size shifts.

Particle Shape/Aspect Ratio (P_(sh))

The benefits of interfacial modification is independent of overallparticle shape. Particles with an aspect ratio of 1 (hollow glassbubbles of iM30K and ceramic G200 microspheres) to 10 (some particularlyirregularly shaped garnet) have been favorably interfacially modified.The current upper limit constraint is associated with challenges ofsuccessful dispersion of fibers within laboratory compounding equipmentwithout significantly damaging the high aspect ratio fibers.Furthermore, inherent rheological challenges are associated with highaspect ratio fibers. With proper engineering, the ability tosuccessfully compound and produce interfacially modify fibers of fiberfragments with aspect ratio in excess of 10 is envisioned.

At a given minor axis particle dimension, the relationship of particleaspect ratio to surface area is given by:

Sphere=πD²; and

ARobject=πD²(r _(a)+0.5);

wherein D is particle size (P_(s)) or diameter, r_(a) is aspect ratio.

For a given minor dimension, the surface area of a particle with anaspect ratio of 10 has 10.5 times the surface area than a sphericalparticle. Dosage levels of interfacial modifier can be adjusted tocompensate for the variance in surface area due to shape effects.

Particle Roughness (P_(r))

Macroscopic particle roughness (defined here as 100× the diameter of theinterfacial modifier) can be defined by the circularity of the particle.It has been shown that interfacially modified mineral or inorganicparticulates with rough and substantially non-spherical shapes obtainthe similar advantageous rheology and physical property results asregularly shaped particles. The circularity or roughness of the particlecan be measured by microscopic inspection of the particles in which anautomated or manual measurement of roughness can be calculated. In sucha measurement, the perimeter of a representative selection of theparticulate is selected and the area of the particle cross section isalso measured. The circularity of the particle is calculated by thefollowing formula:

Circularity=(perimeter)²/area.

Such materials such as hollow glass bubbles have a circularity of 4π(for smooth spherical particles) to 50 (smooth particles with an aspectratio of 10). Many inorganic and mineral particulate have an oblong,multi lobe, rough non-regular shape or aspect. Such materials have acircularity of 13 to 35 or 13 to 30 and obtain the improved viscoelasticproperties of the invention. Using proper optical and image analysistechniques the decoupling of surface roughness and aspect ratio can bedetermined under the appropriate magnification to quantify large scaleparticle roughness. The multiplier for the derivation of the particlemorphology index must be adjusted for the aspect ratio of the particle.

An alternative to optical procedures consists of using a BET analysis todetermine the specific surface area of the particulate phase. Thespecific surface area captures both the macroscopic particle roughnessand particle porosity discussed below for particles of a specificparticle size and shape distribution.

Particle Porosity (P_(p))

The interfacial modifiers are quite large, on the order of a few hundredto a few thousand molecular weight. Within a class of compounds, theeffective diameter of the modifier molecule is proportional to themolecular weight. The predicted diameter of the NZ-12 zirconate modifieris 2260 picometer with a molecular weight of 2616 g/mol. The minimumsize of the modifier molecules would be about 400 picometer (assuming amolecular weight of 460 g/mol). The size of the titanate modifiers wouldbe slightly smaller than the corresponding zirconate for a correspondinggiven organophosphate structure.

Literature review of BET surface analysis reveals a large difference inparticle surface area of mineral particles (from 0.1 to >100 m²-gm⁻¹).Nonporous spheres with a diameter of 1,500 micron results in a specificarea of 0.017 m²-gm⁻¹. In all cases, successful interfacial modificationof the particulates is possible via changes in modifier loading. It isimportant to note that required increase in dosage is not directlyproportional to the BET surface measurements. The pore size penetrableby the BET probing gas is significantly smaller (20.5 A² for krypton forexample) than the interfacial modifier. Silica sand had a pore size of0.90 nm as determined by BET analysis, the interfacial modifier moleculeis able to bridge the pore opening. It will be possible to successfullyinterfacially modify porous absorbents such that the particles compositerheology is improved while absorbent properties of the particulate aremaintained due to the relative size differences in the interfacialmodifier (large), pore size being bridged (small), and the size of theabsorbent molecule (nitrogen, argon, water, etc.) diffusing through theinterfacial modifier into the absorbent particulate.

The particle morphology index is defined as:

PMI=(P_(s))(P_(sh))(P_(r))(P_(p))

For large, spherical, smooth, non-porous particles the particlemorphology index=1 to 200. For small, rough, porous particles with anaspect ratio of 10, the maximum particle morphologyindex=100×10.5×100/0.1=10⁶. Certain particles with a range of particlesize (P_(s)) or diameters and aspect ratios, some roughness and porositycan range from 200 to 10⁴. Other particles with a broadened range ofsizes or diameters and aspect ratios, substantial roughness andincreased porosity can range from 2×10⁴ to 10⁶. The amount ofinterfacial modifier increases with the particle morphology index.

The result of the above particle attributes (particle size anddistribution, particle shape, and roughness) results in a specificparticle packing behavior. The relationship of these variables leads toa resultant packing fraction. Packing fraction is defined as:

P_(f)=P_(d) /d _(pync)

wherein P_(f)=packing fraction; P_(d)=packing density andd_(pync)=pyncnometer density. The relationship of these variables uponparticle packing behavior is well characterized and used within powderedmetallurgy science. For the case of spherical particles, it is wellknown that particle packing increases when the size difference betweenlarge to small particles increases. With a size ratio of 73 parts byweight large particle:27 parts by weight small, monodispersed sphereswith a 7:1 size ratio, the small particles can fit within interstitialspaces of the large particles resulting in a packing level of about 86volume percent. In practice, it is not possible to attain monodispersedspheres. We have found that increased packing is best when usingparticles of broad particle size distribution with as large of a sizedifference between them as possible. In cases like these, we have foundpacking percentages approaching 80 volume %.

For composites containing high volumetric loading of sphericalparticles, the rheological behavior of the highly packed compositesdepends on the characteristics of the contact points between theparticles and the distance between particles. When forming compositeswith polymeric volumes approximately equal to the excluded volume of theparticulate phase, inter-particle interaction dominates the behavior ofthe material. Particles contact one another and the combination ofinteracting sharp edges, soft surfaces (resulting in gouging) and thefriction between the surfaces prevent further or optimal packing.Interfacial modifying chemistries are capable of altering the surface ofthe particulate by coordination bonding, van der Waals forces, covalentbonding, or a combination of all three. The surface of the interfaciallymodified particle behaves as a particle of the interfacial modifier.These organics reduce the friction between particles preventing gougingand allowing for greater freedom of movement between particles. Thebenefits of utilizing particles in the aforementioned acceptableparticle morphology index range does not become evident until packing toa significant proportion of the maximum packing fraction; this value istypically greater than approximately 40 volume % particle phase of thecomposite.

The spatial character of the particles of the invention can be definedby the circularity of the particle and by its aspect ratio. Onesurprising aspect of the invention is that even a particle that departfrom smooth spherical particle shape and are non-spherical or havesubstantial aspect ratio are efficiently packed in the composite of theinvention. Mineral or inorganic particulates with amorphous, rough andsubstantially non-spherical shapes obtain the same advantageous rheologyas regularly shaped particles. The aspect ratio of the more regularparticles of the invention should be less than 1:5 and often less than1:1.5. Similarly, the particulate with an aspect ratio of less than 10or about 5:1 also obtain the benefits of the composites of theinvention.

We have found that the use of the interfacial modifier disclosed in thisapplication obtains a close association of both spherical andsubstantially aspherical particles such that effective composites can bemade even with particles that depart from the ideal spherical particle.Many inorganic or mineral particles, depending on source and processingcan have a narrow particle size distribution, a very regular surface, alow aspect ratio and substantial secularity while other such particlescan have a very amorphous non-regular geometry and surfacecharacteristic. We have found that the processes of the invention andthe composites made using the interfacial modifier of the invention canobtain useful composites from most particle species disclosed herein.

In the composites of the invention, the van der Waals' forces occurbetween collections of hollow glass microspheres that act as “molecules”in the form of crystals or other mineral particle aggregates. Thecomposite of the invention is characterized by a composite havingintermolecular forces between glass microsphere, non-metal, inorganic ormineral particulates that are in the range of van der Waals' strength,i.e., ranges and definitions if appropriate.

In a composite, the hollow glass microsphere is usually much strongerand stiffer than the matrix, and gives the composite its designedproperties. The matrix holds the hollow glass microspheres in an orderlyhigh-density pattern. Because the hollow glass microspheres are usuallydiscontinuous, the matrix also helps to transfer load among the hollowglass microspheres. Processing can aid in the mixing and filling of thehollow glass microsphere in the composite. To aid in the mixture, asurface chemical reagent can help to overcome the forces that preventthe matrix from forming a substantially continuous phase of thecomposite. The tunable composite properties arise from the intimateassociation obtained by use of careful processing and manufacture. Webelieve a surface chemical reagent is an organic material that providesan exterior coating on the particulate promoting the close associationof polymer and particulate. Minimal amounts of the interfacial modifiercan be used including about 0.005 to 8 wt.-%, or about 0.02 to 3 wt. %.Higher amounts are used to coat materials with increased morphology.

Hollow glass spheres (including both hollow and solid) are a usefulnon-metal or inorganic particulate. These spheres are strong enough toavoid being crushed or broken during further processing of the polymericcompound, such as by high pressure spraying, kneading, extrusion orinjection molding. In many cases these spheres have densities close to,but more or less, than that of the polymeric compound into which theyare introduced in order that they distribute evenly within the compoundupon introduction and mixing. Furthermore, it is desirable that thesespheres be resistant to leaching or other chemical interaction withtheir associated polymeric compound. The method of expanding solid glassparticles into hollow glass spheres by heating is well known. See, e.g.,U.S. Pat. No. 3,365,315. Glass is ground to particulate form and thenheated to cause the particles to become plastic and for gaseous materialwithin the glass to act as a blowing agent to cause the particles toexpand. During heating and expansion, the particles are maintained in asuspended state either by directing gas currents under them or allowingthem to fall freely through a heating zone. Sulfur, or compounds ofoxygen and sulfur, serves as the principal blowing agent.

A number of factors affect the density, size, strength, chemicaldurability and yield (the percentage by weight or volume of heatedparticles that become hollow) of hollow glass spheres. These factorsinclude the chemical composition of the glass; the sizes of theparticles fed into the furnace; the temperature and duration of heatingthe particles; and the chemical atmosphere (e.g., oxidizing or reducing)to which the particles are exposed during heating. The percentage ofsilica (SiO₂) in glass used to form hollow glass spheres should bebetween 65 and 85 percent by weight and that a weight percentage of SiO₂below 60 to 65 percent would drastically reduce the yield of the hollowspheres.

Useful hollow glass spheres having average densities of about 0.1grams-cm⁻³ to approximately 0.7 grams-cm⁻³ or about 0.125 grams-cm⁻³ toapproximately 0.6 grams-cm⁻³ are prepared by heating solid glassparticles.

For a product of hollow glass spheres having a particular desiredaverage density, there is an optimum sphere range of sizes of particlesmaking up that product which produces the maximum average strength. Acombination of a larger and a smaller hollow glass sphere wherein thereis about 0.1 to 25 wt. % of the smaller sphere and about 99.9 to about75 wt. % of larger particles can be used were the ratio of the particlesize (P_(s)) of the larger particles to the ratio of the smaller isabout 2-7:1.

Hollow glass spheres used commercially can include both solid and hollowglass spheres. All the particles heated in the furnace do not expand,and most hollow glass-sphere products are sold without separating thehollow from the solid spheres.

Preferred hollow glass spheres are hollow spheres with relatively thinwalls. Such spheres typically comprise a silica-line-oral silicatehollow glass and in bulk form appear to be a white powdery particulate.The density of the hollow spherical materials tends to range from about0.1 to 0.8 g/cc this substantially water insoluble and has an averageparticle size (P_(s)) that ranges from about 10 to 250 microns.

In the past, an inorganic hollow glass sphere has been used in polymerssuch as nylon, ABS, or polycarbonate compositions or alloys thereof. Innylons, at a particulate loading ranges from a few percent to as much as20 vol. %, however, in our view, the prior art inorganic materialsbecome brittle and lose their viscoelastic character as the volumepercentage of particulate exceeds 20 or 25 vol. %. In Applicantscompositions, the materials maintain both an effective compositeformation of loadings of greater than 20% but also maintain substantialviscoelasticity and polymer characteristics at polymer loadings thatrange greater than 25 vol. %, greater than 35 vol. %, greater than 40vol. % and typically range from about 40 vol. % to as much as 95 vol. %.In these ranges of particulate loading, the composites in theapplication maintain the viscoelastic properties of the polymer in thepolymer phase. As such within these polymer loadings, Applicants haveobtained useful elongation at break wherein the elongations can be inexcess of 5%, in excess of 10%, in excess of 20%, and can range fromabout 20 to 500% elongation at break. Further, the tensile yield pointcan substantially exceed the prior art materials and can range fromabout 5 to 10% elongation.

Typically, the composite materials of the invention are manufacturedusing melt processing and are also utilized in product formation usingmelt processing. A typical thermoplastic polymer material, is combinedwith particulate and processed until the material attains (e.g.) auniform density (if density is the characteristic used as adeterminant). Alternatively, in the manufacture of the material, thenon-metal, inorganic or mineral or the thermoplastic polymer may beblended with interfacial modification agents and the modified materialscan then be melt processed into the material. Once the material attainsa sufficient property, such as, for example, density, the material canbe extruded into a product or into a raw material in the form of apellet, chip, wafer, proform or other easily processed material usingconventional processing techniques.

In the manufacture of useful products with the composites of theinvention, the manufactured composite can be obtained in appropriateamounts, subjected to heat and pressure, typically in extruder equipmentand then formed into an appropriate shape having the correct amount ofmaterials in the appropriate physical configuration. In the appropriateproduct design, during composite manufacture or during productmanufacture, a pigment or other dye material can be added to theprocessing equipment. One advantage of this material is that aninorganic dye or pigment can be co-processed resulting in a materialthat needs no exterior painting or coating to obtain an attractive,functional, or decorative appearance. The pigments can be included inthe polymer blend, can be uniformly distributed throughout the materialand can result in a surface that cannot chip, scar or lose itsdecorative appearance. One particularly important pigment materialcomprises titanium dioxide (TiO₂). This material is non-toxic, is abright white particulate that can be easily combined with eithernon-metal, inorganic or mineral particulates and/or polymer compositesto enhance the novel characteristics of the composite material and toprovide a white hue to the ultimate composite material.

We have further found that a blend of two, three or more non-metal,inorganic or minerals in particulate form can, obtain importantcomposite properties from all of non-metal, inorganic or minerals in apolymer composite structure. Such composites each can have unique orspecial properties. These composite processes and materials have theunique capacity and property that the composite acts as blendedcomposite of two or three different non-metal, inorganic or mineralsthat could not, due to melting point and other processing difficulties,be made into a blend without the methods of the invention.

A large variety of polymer materials can be used in the compositematerials of the invention. For the purpose of this application, apolymer is a general term covering either a thermoset or athermoplastic. We have found that polymer materials useful in theinvention include both condensation polymeric materials and addition orvinyl polymeric materials. Included are both vinyl and condensationpolymers, and polymeric alloys thereof. Vinyl polymers are typicallymanufactured by the polymerization of monomers having an ethylenicallyunsaturated olefinic group. Condensation polymers are typically preparedby a condensation polymerization reaction which is typically consideredto be a stepwise chemical reaction in which two or more moleculescombined, often but not necessarily accompanied by the separation ofwater or some other simple, typically volatile substance. Such polymerscan be formed in a process called polycondensation. The polymer has adensity of at least 0.85 gm-cm⁻³, however, polymers having a density ofgreater than 0.96 are useful to enhance overall product density. Adensity is often up to 1.7 or up to 2 gm-cm⁻³ or can be about 1.5 to1.95 gm-cm⁻³.

Vinyl polymers include polyethylene, polypropylene, polybutylene,acrylonitrile-butadiene-styrene (ABS), polybutylene copolymers,polyacetyl resins, polyacrylic resins, homopolymers or copolymerscomprising vinyl chloride, vinylidene chloride, fluorocarbon copolymers,etc. Condensation polymers include nylon, phenoxy resins, polyarylethersuch as polyphenylether, polyphenylsulfide materials; polycarbonatematerials, chlorinated polyether resins, polyethersulfone resins,polyphenylene oxide resins, polysulfone resins, polyimide resins,thermoplastic urethane elastomers and many other resin materials.

Condensation polymers that can be used in the composite materials of theinvention include polyamides, polyamide-imide polymers,polyarylsulfones, polycarbonate, polybutylene terephthalate,polybutylene naphthalate, polyetherimides, polyethersulfones,polyethylene terephthalate, thermoplastic polyamides, polyphenyleneether blends, polyphenylene sulfide, polysulfones, thermoplasticpolyurethanes and others. Preferred condensation engineering polymersinclude polycarbonate materials, polyphenyleneoxide materials, andpolyester materials including polyethylene terephthalate, polybutyleneterephthalate, polyethylene naphthalate and polybutylene naphthalatematerials.

Polycarbonate engineering polymers are high performance, amorphousengineering thermoplastics having high impact strength, clarity, heatresistance and dimensional stability. Polycarbonates are generallyclassified as a polyester or carbonic acid with organic hydroxycompounds. The most common polycarbonates are based on phenol A as ahydroxyl compound copolymerized with carbonic acid. Materials are oftenmade by the reaction of a biphenyl A with phosgene (O═CCl₂).Polycarbonates can be made with phthalate monomers introduced into thepolymerization extruder to improve properties such as heat resistance,further trifunctional materials can also be used to increase meltstrength or extrusion blow molded materials. Polycarbonates can often beused as a versatile blending material as a component with othercommercial polymers in the manufacture of alloys. Polycarbonates can becombined with polyethylene terephthalateacrylonitrile-butadiene-styrene, styrene maleic anhydride and others.Preferred alloys comprise a styrene copolymer and a polycarbonate.Preferred polycarbonate materials should have a melt index between 0.5and 7, preferably between 1 and 5 gms/10 min.

A variety of polyester condensation polymer materials includingpolyethylene terephthalate, polybutylene terephthalate, polyethylenenaphthalate, polybutylene naphthalate, etc. can be useful in thecomposites of the invention. Polyethylene terephthalate and polybutyleneterephthalate are high performance condensation polymer materials. Suchpolymers often made by a copolymerization between a diol (ethyleneglycol, 1,4-butane diol) with dimethyl terephthalate. In thepolymerization of the material, the polymerization mixture is heated tohigh temperature resulting in the transesterification reaction releasingmethanol and resulting in the formation of the engineering plastic.Similarly, polyethylene naphthalate and polybutylene naphthalatematerials can be made by copolymerizing as above using as an acidsource, a naphthalene dicarboxylic acid. The naphthalate thermoplasticshave a higher Tg and higher stability at high temperature compared tothe terephthalate materials. However, all these polyester materials areuseful in the composite materials of the invention. Such materials havea preferred molecular weight characterized by melt flow properties.Useful polyester materials have a viscosity at 265° C. of about 500-2000cP, preferably about 800-1300 cP.

Polyphenylene oxide materials are engineering thermoplastics that areuseful at temperature ranges as high as 330° C. Polyphenylene oxide hasexcellent mechanical properties, dimensional stability, and dielectriccharacteristics. Commonly, phenylene oxides are manufactured and sold aspolymer alloys or blends when combined with other polymers or fiber.Polyphenylene oxide typically comprises a homopolymer of2,6-dimethyl-1-phenol. The polymer commonly known aspoly(oxy-(2,6-dimethyl-1,4-phenylene)). Polyphenylene is often used asan alloy or blend with a polyamide, typically nylon 6-6, alloys withpolystyrene or high impact styrene and others. A preferred melt index(ASTM 1238) for the polyphenylene oxide material useful in the inventiontypically ranges from about 1 to 20, preferably about 5 to 10 gm/10 min.The melt viscosity is about 1000 cP at 265° C.

Another class of thermoplastic include styrenic copolymers. The termstyrenic copolymer indicates that styrene is copolymerized with a secondvinyl monomer resulting in a vinyl polymer. Such materials contain atleast a 5 mol-% styrene and the balance being 1 or more other vinylmonomers. An important class of these materials are styreneacrylonitrile (SAN) polymers. SAN polymers are random amorphous linearcopolymers produced by copolymerizing styrene acrylonitrile andoptionally other monomers. Emulsion, suspension and continuous masspolymerization techniques have been used. SAN copolymers possesstransparency, excellent thermal properties, good chemical resistance andhardness. These polymers are also characterized by their rigidity,dimensional stability and load bearing capability. Olefin modified SAN's(OSA polymer materials) and acrylic styrene acrylonitriles (ASA polymermaterials) are known. These materials are somewhat softer thanunmodified SAN's and are ductile, opaque, two phased terpolymers thathave surprisingly improved weatherability.

ASA polymers are random amorphous terpolymers produced either by masscopolymerization or by graft copolymerization. In mass copolymerization,an acrylic monomer styrene and acrylonitrile are combined to form aheteric terpolymer. In an alternative preparation technique, styreneacrylonitrile oligomers and monomers can be grafted to an acrylicelastomer backbone. Such materials are characterized as outdoorweatherable and UV resistant products that provide excellentaccommodation of color stability property retention and propertystability with exterior exposure. These materials can also be blended oralloyed with a variety of other polymers including polyvinyl chloride,polycarbonate, polymethyl methacrylate and others. An important class ofstyrene copolymers includes the acrylonitrile-butadiene-styrenemonomers. These polymers are very versatile family of engineeringthermoplastics produced by copolymerizing the three monomers. Eachmonomer provides an important property to the final terpolymer material.The final material has excellent heat resistance, chemical resistanceand surface hardness combined with processability, rigidity andstrength. The polymers are also tough and impact resistant. The styrenecopolymer family of polymers have a melt index that ranges from about0.5 to 25, preferably about 0.5 to 20.

An important class of engineering polymers that can be used in thecomposites of the invention include acrylic polymers. Acrylics comprisea broad array of polymers and copolymers in which the major monomericconstituents are an ester acrylate or methacrylate. These polymers areoften provided in the form of hard, clear sheet or pellets. Acrylicmonomers polymerized by free radical processes initiated by typicallyperoxides, azo compounds or radiant energy. Commercial polymerformulations are often provided in which a variety of additives aremodifiers used during the polymerization provide a specific set ofproperties for certain applications. Pellets made for polymer gradeapplications are typically made either in bulk (continuous solutionpolymerization), followed by extrusion and pelleting or continuously bypolymerization in an extruder in which unconverted monomer is removedunder reduced pressure and recovered for recycling. Acrylic plastics arecommonly made by using methyl acrylate, methylmethacrylate, higher alkylacrylates and other copolymerizable vinyl monomers. Preferred acrylicpolymer materials useful in the composites of the invention has a meltindex of about 0.5 to 50, preferably about 1 to 30 gm/10 min.

Vinyl polymer polymers include a acrylonitrile; polymer of alpha-olefinssuch as ethylene, propylene, etc.; chlorinated monomers such as vinylchloride, vinylidene dichloride, acrylate monomers such as acrylic acid,methylacrylate, methylmethacrylate, acrylamide, hydroxyethyl acrylate,and others; styrenic monomers such as styrene, alphamethyl styrene,vinyl toluene, etc.; vinyl acetate; and other commonly availableethylenically unsaturated monomer compositions.

Polymer blends or polymer alloys can be useful in manufacturing thepellet or linear extrudate of the invention. Such alloys typicallycomprise two miscible polymers blended to form a uniform composition.Scientific and commercial progress in the area of polymer blends haslead to the realization that important physical property improvementscan be made not by developing new polymer material but by formingmiscible polymer blends or alloys. A polymer alloy at equilibriumcomprises a mixture of two amorphous polymers existing as a single phaseof intimately mixed segments of the two macro molecular components.Miscible amorphous polymers form glasses upon sufficient cooling and ahomogeneous or miscible polymer blend exhibits a single, compositiondependent glass transition temperature (Tg). Immiscible or non-alloyedblend of polymers typically displays two or more glass transitiontemperatures associated with immiscible polymer phases. In the simplestcases, the properties of polymer alloys reflect a composition weightedaverage of properties possessed by the components. In general, however,the property dependence on composition varies in a complex way with aparticular property, the nature of the components (glassy, rubbery orsemi-crystalline), the thermodynamic state of the blend, and itsmechanical state whether molecules and phases are oriented.

The primary requirement for the substantially thermoplastic engineeringpolymer material is that it retains sufficient thermoplastic propertiessuch as viscosity and stability, to permit melt blending with aparticulate, permit formation of linear extrudate pellets, and to permitthe composition material or pellet to be extruded or injection molded ina thermoplastic process forming the useful product. Engineering polymerand polymer alloys are available from a number of manufacturersincluding Dyneon LLC, B.F. Goodrich, G.E., Dow, and duPont.

Polyester polymers are manufactured by the reaction of a dibasic acidwith a glycol. Dibasic acids used in polyester production includephthalic anhydride, isophthalic acid, maleic acid and adipic acid. Thephthalic acid provides stiffness, hardness and temperature resistance;maleic acid provides vinyl saturation to accommodate free radical cure;and adipic acid provides flexibility and ductility to the cured polymer.Commonly used glycols are propylene glycol which reduces crystallinetendencies and improves solubility in styrene. Ethylene glycol anddiethylene glycol reduce crystallization tendencies. The diacids andglycols are condensed eliminating water and are then dissolved in avinyl monomer to a suitable viscosity. Vinyl monomers include styrene,vinyltoluene, paramethylstyrene, methylmethacrylate, and diallylphthalate. The addition of a polymerization initiator, such ashydroquinone, tertiary butylcatechol or phenothiazine extends the shelflife of the uncured polyester polymer. Polymers based on phthalicanhydride are termed orthophthalic polyesters and polymers based onisophthalic acid are termed isophthalic polyesters. The viscosity of theunsaturated polyester polymer can be tailored to an application. Lowviscosity is important in the fabrication of fiber-reinforced compositesto ensure good wetting and subsequent high adhesion of the reinforcinglayer to the underlying substrate. Poor wetting can result in largelosses of mechanical properties. Typically, polyesters are manufacturedwith a styrene concentration or other monomer concentration producingpolymer having an uncured viscosity of 200-1,000 mPa·s(cP). Specialtypolymers may have a viscosity that ranges from about 20 cP to 2,000 cP.Unsaturated polyester polymers are typically cured by free radicalinitiators commonly produced using peroxide materials. Wide varieties ofperoxide initiators are available and are commonly used. The peroxideinitiators thermally decompose forming free radical initiating species.

Phenolic polymers can also be used in the manufacture of the structuralmembers of the invention. Phenolic polymers typically comprise aphenol-formaldehyde polymer. Such polymers are inherently fireresistant, heat resistant and are low in cost. Phenolic polymers aretypically formulated by blending phenol and less than a stoichiometricamount of formaldehyde. These materials are condensed with an acidcatalyst resulting in a thermoplastic intermediate polymer calledNOVOLAK. These polymers are oligomeric species terminated by phenolicgroups. In the presence of a curing agent and optional heat, theoligomeric species cure to form a very high molecular weight thermosetpolymer. Curing agents for novalaks are typically aldehyde compounds ormethylene (—CH₂—) donors. Aldehydic curing agents includeparaformaldehyde, hexamethylenetetramine, formaldehyde, propionaldehyde,glyoxal and hexamethylmethoxy melamine.

The fluorocarbon polymers useful in this invention are perflourinatedand partially fluorinated polymers made with monomers containing one ormore atoms of fluorine, or copolymers of two or more of such monomers.Common examples of fluorinated monomers useful in these polymers orcopolymers include tetrafluoroethylene (TFE), hexafluoropropylene(HFP),vinylidene fluoride (VDF), perfluoroalkylvinyl ethers such asperfluoro-(n-propyl-vinyl) ether (PPVE) or perfluoromethylvinylether(PMVE). Other copolymerizable olefinic monomers, includingnon-fluorinated monomers, may also be present.

Particularly useful materials for the fluorocarbon polymers areTFE-HFP-VDF terpolymers (melting temperature of about 100 to 260° C.;melt flow index at 265° C. under a 5 kg load is about 1-30 g-10hexafluoropropylene-tetrafluoroethylene-ethylene (HTE) terpolymers(melting temperature about 150 to 280° C.; melt flow index at 297° C.under a 5 kg load of about 1-30 g-10 ethylene-tetrafluoroethylene (ETFE)copolymers (melting temperature about 250 to 275° C.; melt flow index at297° C. under a 5 kg load of about 1-30 g-10hexafluoropropylene-tetrafluoroethylene (FEP) copolymers (meltingtemperature about 250 to 275° C.; melt flow index at 372° C. under a 5kg load of about 1-30 g-10 min⁻¹.), andtetrafluoroethylene-perfluoro(alkoxy alkane) (PFA) copolymers (meltingtemperature about 300 to 320° C.; melt flow index at 372° C. under a 5kg load of about 1-30 g-10 min⁻¹.). Each of these fluoropolymers iscommercially available from Dyneon LLC, Oakdale, Minn. The TFE-HFP-VDFterpolymers are sold under the designation “THV”.

Also useful are vinylidene fluoride polymers primarily made up ofmonomers of vinylidene fluoride, including both homo polymers andcopolymers. Such copolymers include those containing at least 50 molepercent of vinylidene fluoride copolymerized with at least one comonomerselected from the group consisting of tetrafluoroethylene,trifluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinylfluoride, pentafluoropropene, and any other monomer that readilycopolymerizes with vinylidene fluoride. These materials are furtherdescribed in U.S. Pat. No. 4,569,978 (Barber) incorporated herein byreference. Preferred copolymers are those composed of from at leastabout 70 and up to 99 mole percent vinylidene fluoride, andcorrespondingly from about 1 to 30 percent tetrafluoroethylene, such asdisclosed in British Patent No. 827,308; and about 70 to 99 percentvinylidene fluoride and 1 to 30 percent hexafluoropropene (see forexample U.S. Pat. No. 3,178,399); and about 70 to 99 mole percentvinylidene fluoride and 1 to 30 percent trifluoroethylene Terpolymers ofvinylidene fluoride, trifluoroethylene and tetrafluoroethylene such asdescribed in U.S. Pat. No. 2,968,649 and terpolymers of vinylidenefluoride, trifluoroethylene and tetrafluoroethylene are alsorepresentative of the class of vinylidene fluoride copolymers which areuseful in this invention. Such materials are commercially availableunder the KYNAR trademark from Arkema Group located in King of Prussia,Pa. or under the DYNEON trademark from Dyneon LLC of Oakdale, Minn.

Fluorocarbon elastomer materials can also be used in the compositematerials of the invention. Fluorocarbon elastomers contain VF₂ and HFPmonomers and optionally TFE and have a density greater than 1.8 gm-cm⁻³;these polymers exhibit good resistance to most oils, chemicals,solvents, and halogenated hydrocarbons, and excellent resistance toozone, oxygen, and weathering. Their useful application temperaturerange is −40° C. to 300° C. Fluorocarbon elastomer examples includethose described in detail in Lentz, U.S. Pat. No. 4,257,699, as well asthose described in Eddy et al., U.S. Pat. No. 5,017,432 and Ferguson etal., U.S. Pat. No. 5,061,965. The disclosures of each of these patentsare totally incorporated herein by reference.

Latex fluorocarbon polymers are available in the form of the polymerscomprising the PFA, FEP, ETFE, HTE, THV and PVDF monomers. Fluorinatedpoly(meth)acrylates can generally be prepared by free radicalpolymerization either neat or in solvent, using radical initiators wellknown to those skilled in the art. Other monomers which can becopolymerized with these fluorinated (meth)acrylate monomers includealkyl (meth)acrylates, substituted alkyl (meth)acrylates, (meth)acrylicacid, (meth)acrylamides, styrenes, vinyl halides, and vinyl esters. Thefluorocarbon polymers can comprise polar constituents. Such polar groupsor polar group containing monomers may be anionic, nonionic, cationic,or amphoteric. In general, the more commonly employed polar groups orpolar group-containing organic radicals include organic acids,particularly carboxylic acid, sulfonic acid and phosphonic acid;carboxylate salts, sulfonates, phosphonates, phosphate esters, ammoniumsalts, amines, amides, alkyl amides, alkyl aryl amides, imides,sulfonamides, hydroxymethyl, thiols, esters, silanes, andpolyoxyalkylenes, as well as other organic radicals such as alkylene orarylene substituted with one or more of such polar groups. The latexfluorocarbon polymers described herein are typically aqueous dispersedsolids but solvent materials can be used. The fluorocarbon polymer cancombined with various solvents to form emulsion, solution or dispersionin a liquid form. Dispersions of fluoropolymers can be prepared usingconventional emulsion polymerization techniques, such as described inU.S. Pat. Nos. 4,418,186; 5,214,106; 5,639,838; 5,696,216 or ModernFluoropolymers, Edited by John Scheirs, 1997 (particularly pp. 71-101and 597-614).

The liquid forms can be further diluted in order to deliver the desiredconcentration. Although aqueous emulsions, solutions, and dispersionsare preferred, up to about 50% of a cosolvent such as methanol,isopropanol, or methyl perfluorobutyl ether may be added. Preferably,the aqueous emulsions, solutions, and dispersions comprise less thanabout 30% cosolvent, more preferably less than about 10% cosolvent, andmost preferably the aqueous emulsions, solutions, and dispersions aresubstantially free of cosolvent.

Interfacial modifiers provide the close association of the particle withthe polymer. Interfacial modifiers used in the non-reactive ornon-crosslinking application fall into broad categories including, forexample, stearic acid derivatives, titanate compounds, zirconatecompounds, phosphonate compounds, aluminate compounds. Aluminates,phosphonates, titanates and zirconates useful contain from about 1 toabout 3 ligands comprising hydrocarbyl phosphate esters and/orhydrocarbyl sulfonate esters and about 1 to 3 hydrocarbyl ligands whichmay further contain unsaturation and heteroatoms such as oxygen,nitrogen and sulfur. Preferably the titanates and zirconates containfrom about 2 to about 3 ligands comprising hydrocarbyl phosphate estersand/or hydrocarbyl sulfonate esters, preferably 3 of such ligands andabout 1 to 2 hydrocarbyl ligands, preferably 1 hydrocarbyl ligand.

The choice of interfacial modifiers is dictated by particulate, polymer,and application. The particle is coated even if having substantialmorphology. The maximum density of a composite is a function of thedensities of the materials and the volume fractions of each. Higherdensity composites are achieved by maximizing the per unit volume of thematerials with the highest densities. The materials are almostexclusively refractory metals such as tungsten or osmium. Thesematerials are extremely hard and difficult to deform, usually resultingin brittle fracture. When compounded with deformable polymeric binders,these brittle materials may be formed into usable shapes usingtraditional thermoplastic equipment. However, the maximum densitiesachievable will be less then optimum. When forming composites withpolymeric volumes approximately equal to the excluded volume of thefiller, inter-particle interaction dominates the behavior of thematerial. Particles contact one another and the combination ofinteracting sharp edges, soft surfaces (resulting in gouging, points areusually work hardened) and the friction between the surfaces preventfurther or optimal packing. Therefore, maximizing properties is afunction of softness of surface, hardness of edges, point size of point(sharpness), surface friction force and pressure on the material,circularity, and the usual, shape size distribution. Because of thisinter-particle friction, the forming pressure will decreaseexponentially with distance from the applied force. Interfaciallymodifying chemistries are capable of modifying the surface of the densefiller by coordination bonding, van der Waals forces, covalent bonding,or a combination of all three. The surface of the particle behaves as aparticle of the interfacial modifier. These organics reduce the frictionbetween particles preventing gouging and allowing for greater freedom ofmovement between particles. These phenomenon allow the applied shapingforce to reach deeper into the form resulting in a more uniform pressuregradient.

Preferred titanates and zirconates include isopropyltri(dioctyl)pyrophosphato titanate (available from Kenrich Chemicalsunder the designation KR38S), neopentyl(diallyl)oxy,tri(dodecyl)benzene-sulfonyl titanate (available from Kenrich Chemicalsunder the trademark and designation LICA 09), neopentyl(diallyl)oxy,trioctylphosphato titanate (available from Kenrich Chemicals under thetrademark and designation LICA 12), neopentyl(diallyl)oxy,tri(dodecyl)benzene-sulfonyl zirconate (available from Kenrich Chemicalsunder the designation NZ 09), neopentyl(diallyl)oxy,tri(dioctyl)phosphato zirconate (available from Kenrich Chemicals underthe designation NZ 12), and neopentyl(diallyl)oxy,tri(dioctyl)pyro-phosphato zirconate (available from Kenrich Chemicalsunder the designation NZ 38). The most preferred titanate istri(dodecyl)benzene-sulfonyl titanate (available from Kenrich Chemicalsunder the designation LICA 09). The interfacial modifiers modify theparticulate in the composites of the invention with the formation of alayer on the surface of the particle reducing the intermolecular forces,improving the tendency of the polymer mix with the particle, andresulting in increased composite density. Density is maximized as thenumber of close association between the particulate surface and polymeris maximized.

Thermosetting polymers can be used in an uncured form to make thecomposites with the interfacial modifiers. Once the composite is formedthe reactive materials can chemically bond the polymer phase if athermoset polymer is selected. The reactive groups in the thermoset caninclude methacrylyl, styryl, or other unsaturated or organic materials.

Thermoplastics include polyvinylchloride, polyphenylene sulfite, acrylichomopolymers, maleic anhydride containing polymers, acrylic materials,vinyl acetate polymers, diene containing copolymers such as1,3-butadiene, 1,4-pentadiene, halogen or chlorosulfonyl modifiedpolymers or other polymers that can react with the composite systems ofthe invention. Condensation polymeric thermoplastics can be usedincluding polyamides, polyesters, polycarbonates, polysulfones andsimilar polymer materials by reacting end groups with silanes havingaminoalkyl, chloroalkyl, isocyanato or similar functional groups.

The manufacture of the particulate composite materials depends on goodmanufacturing technique. Often the particulate is initially treated withan interfacial modifier by spraying the particulate with a solution ofinterfacial modifier on the particle with blending and drying carefullyto ensure uniform particulate coating. interfacial modifier can also beadded to particles in bulk blending operations using high intensityLittleford or Henschel blenders. Alternatively, twin cone mixers can befollowed by drying or direct addition to a screw compounding device.Interfacial modifiers may also be reacted with the particulate inaprotic solvent such as toluene, tetrahydrofuran, mineral spirits orother such known solvents.

The particulate can be interfacially combined into the polymer phasedepending on the nature of the polymer phase, the filler, theparticulate surface chemistry and any pigment process aid or additivepresent in the composite material. In general, the mechanism used tocouple particulate to polymer include solvation, chelation, coordinationbonding (ligand formation), etc. Typically, however, covalent bonds,linking the particle or interfacial modifier, and the polymer is notformed. Titanate, phosphonate or zirconate agents can be used. Suchagents have the following formula:

(RO)_(m)—Ti—(O—X—R′—Y)_(n)

(RO)_(m)—Zr—(O—X—W—Y)_(n)

(RO)_(m)—P—(O—X—R′—Y)_(n)

wherein R and R′ are independently a hydrocarbyl, C1-C12 alkyl group ora C7-20 alkyl or alkaryl group wherein the alkyl or alkaryl groups mayoptionally contain one or more oxygen atoms or unsaturation; X issulfate or phosphate; Y is H or any common substituent for alkyl or arylgroups; m and n are 1 to 3. Titanates provide antioxidant properties andcan modify or control cure chemistry. Zirconate provides excellent bondstrength but maximizes curing, reduces formation of off color informulated thermoplastic materials. A useful zirconate material isneopentyl(diallyl) oxy-tri (dioctyl) phosphato-zirconate.

The composite materials having the desired physical properties can bemanufactured as follows. In a preferred mode, the surface of theparticulate is initially prepared, the interfacial modifier is coated onthe prepared particle material, and the resulting product is isolatedand then combined with the continuous polymer phase to affect aninterfacial association between the particulate and the polymer. Oncethe composite material is prepared, it is then formed into the desiredshape of the end use material. Solution processing is an alternativethat provides solvent recovery during materials processing. Thematerials can also be dry-blended without solvent. Blending systems suchas ribbon blenders obtained from Drais Systems, high density driveblenders available from Littleford Brothers and Henschel are possible.Further melt blending using Banberry, veferralle single screw or twinscrew compounders is also useful. When the materials are processed as aplastisol or organosol with solvent, liquid ingredients are generallycharged to a processing unit first, followed by polymer polymer,particulate and rapid agitation. Once all materials are added a vacuumcan be applied to remove residual air and solvent, and mixing iscontinued until the product is uniform and high in density.

Dry blending is generally preferred due to advantages in cost. Howevercertain embodiments can be compositionally unstable due to differencesin particle size. In dry blending processes, the composite can be madeby first introducing the polymer, combining the polymer stabilizers, ifnecessary, at a temperature from about ambient to about 60° C. with thepolymer, blending a particulate (modified if necessary) with thestabilized polymer, blending other process aids, interfacial modifier,colorants, indicators or lubricants followed by mixing in hot mix,transfer to storage, packaging or end use manufacture.

Interfacially modified materials can be made with solvent techniquesthat use an effective amount of solvent to initiate formation of acomposite. When interfacial treatment is substantially complete, thesolvent can be stripped. Such solvent processes are conducted asfollows:

-   -   1) Solvating the interfacial modifier or polymer or both;    -   2) Mixing the particulate into a bulk phase or polymer master        batch: and    -   3) Devolatilizing the composition in the presence of heat &        vacuum above the Tg of the polymer.

When compounding with twin screw compounders or extruders, a preferredprocess can be used involving twin screw compounding as follows.

1. Add particulate and raise temperature to remove surface water (barrel1).

2. Add interfacial modifier to twin screw when filler is at temperature(barrel 3).

3. Disperse/distribute surface chemical treatment on particulate.

4. Maintain temperature to completion.

5. Vent by-products (barrel 6).

6. Add polymer binder (barrel 7).

7. Compress/melt polymer binder.

8. Disperse/distribute polymer binder in particulate.

9. Combine modified particulate with polymer binder.

10. Vacuum degas remaining products (barrel 9).

11. Compress resulting composite.

12. Form desired shape, pellet, lineal, tube, injection mold article,etc. through a die or post-manufacturing step.

Alternatively in formulations containing small volumes of continuousphase:

1. Add polymer binder.

2. Add interfacial modifier to twin screw when polymer binder is attemperature.

3. Disperse/distribute interfacial modifier in polymer binder.

4. Add filler and disperse/distribute particulate.

5 Raise temperature

6. Maintain temperature to completion.

7. Compress resulting composite.

8. Form desired shape, pellet, lineal, tube, injection mold article,etc. through a die or post-manufacturing step.

Certain selections of polymers and particulates may permit the omissionof the interfacial modifier and their related processing steps.

Experimental Section

THV220A (Dyneon Polymers, Oakdale Minn.) is a polymer oftetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. Thematerial is intended for extrusion applications, has a melting point of120° C. and a specific gravity of 1.9 g/cc.

NZ 12 is neopentyl(diallyl)oxy-tri(dioctyl)phosphato-zirconate. It isavailable from KenRich Petrochemicals (Bayonne, N.J.). NZ12 has aspecific gravity of 1.06 g/cc and is readily soluble in isopropylalcohol (IPA).

Methods and Procedures Powder Characterizations:

Powder characterization is completed to determine packing behavior ofthe powdered materials. Packing fraction is determined by dividing thepacking density of the powder by the true density as determined viahelium pycnometry.

Packing fraction is defined as:

P_(f)=P_(d) /d _(pync)

wherein P_(f)=packing fraction; P_(d)=packing density andd_(pync)=pyncnometer density.

Packing density is determined by measuring the bulk powder weight withina volume. The packing density is commonly determined by placing thepowder within a metallurgical press. The press setup is available fromBuehler International (Lake Bluff, IL). For frangible materials,pressure is reduced to the appropriate level to reduce breakage of thepowder particles thereby preventing artificially high packing densityvalues. For very frangible materials, a tap density is used. Thepycnometer density is determined by helium gas pycnometry (AccuPync 1330manufactured by Micromeretics Corporation—Norcross, Ga.).

Application of Interfacial Modifier:

To interfacially modifiy particles at a lab scale, the interfacialmodifier is first soluabilized with isopropyl alcohol (IPA). TheIPA/modifier mixture is applied to the powdered material previouslyplaced within a rotating stainless steel rotating cooking stock pot. The3 gallon stainless steel cooking pot was coupled to a DC drive and motorfor controlled rotation with the pot orientated at 30 degrees fromhorizontal. The IPA/modifier mixture is added along with additional IPAin enough volume to fully wet and flood the particles. The outer part ofthe pot is then heated externally with an industrial heat gun tovolatize the IPA. After a sufficient time, the modified particles becomefree flowing—an indication that they are ready for compounding withinour laboratory twin screw compounding equipment.

Compounding:

The polymer and modified particles are fed in appropriate ratios usingK-tron K20 gravimetric weight loss feeders. The raw ingredients arefused together within a 19 mm B&P twin screw compounder. Barrel zonetemperatures (5), screw speed, volumetric throughput, and diecharacteristics (number of openings and opening diameter) are varieddepending on the nature of the particles and polymers being compounded.Commonly, torque, pressure, and melt temperature are monitoredresponses. A useful way to ensure the proper ratio of polymer andparticulate(s) is to place compounded pellets into the heatedmetallurgical press; we call this the “puck density”.

Extrusion:

The compounded products are extruded using 1″ diameter extruder (Al—BeIndustries, Fullerton, Calif.). Temperatures and volumetric throughputvary depending on the rheological behavior of the materials beingextruded. Typically, motor amp load and extrusion pressures aremonitored responses and used to gauge ease of extudability. For samplesrequiring characterization of tensile properties, the materials areextruded through a 19 mm×3 mm rectangular die plate onto a moving beltto minimize extrudate draw-down.

Tensile and Elongation:

ASTM Type IV dogbones were die cut from the extruded strips. Thedog-bones were then tensile tested using a Lloyd Instruments universaltesting machine produced by Ametek, Inc. A one-inch gauge length wasused in the strain calculations. The cross-head speed was varied in anattempt to meet ASTM standards of tensile test duration lasting between30 seconds and 3 minutes. A stress/strain curve was generated for thetest samples.

Example 1 Hollow Glass Spheres

A supply of iM30k hollow glass bubbles were obtained from 3M Corporation(St. Paul, Minn.). The bubbles possess a density of approximately 0.6g/cc. The bubbles were interfacailly modified with KR238S (KenRichChemicals) with 4.8 parts of interfacial modifier to 100 partsparticulate. The polymer phase was THV220 from Dyneon (St. Paul, Minn.).The bubbles were compounded into the polymer phase to a loading of 60volume % hollow glass bubbles in the polymer phase. Samples were thenextruded and ASTM tensile dogbones specimens made and tensile tested.Additionally, puck samples were made via the metallurgical press toconfirm the formulations were near the targeted values.

Obvious differences were apparent during compounding. The productwithout modifier was brown/tan in color exiting the die plate,indicating degradation of the material. Additionally, the bubbles didnot feed well and bridged at the infeed throat of the machine. As aresult, the volumetric throughput had to be reduced from 60 to 40 ml perminute. The puck density of the compounded product was 1.23 g/cc,indicating that many glass bubbles broke during compounding (a value of1.10 g/cc would be obtained at the target loading without any glassbubble breakage). The composite products were brittle; failing at anelongation of about 0.3 inches (FIG. 2).

The composite containing the interfacially modified glass bubblespossessed lower density (1.15 g/cc vs 1.23 g/cc) indicating less bubblesbroke during processing and that the final composite contained moreintact glass bubbles than the composite with the unmodified bubbles.Additionally, the particles fed well into the throat of the compounderthereby allowing a volumetric throughput of 60 ml per minute to bemaintained. The composite exiting the compounder die plate was white.The extruded composite was very flexible, elongating to about 5 to 8inches at break (FIG. 4).

iM30k hollow glass bubbles were obtained from 3M Corporation (St. Paul,Minn.). The bubbles possessed a density of approximately 0.62 g/cc. Theconcept that successful loading of the hollow glass spheres at highvolumetric loading within a composite would have exceptionally lowdensity and possibly other benefits as well (namely low thermal andacoustical conduction etc.) was conceived. Varying levels of NZ-12 wereapplied to the glass beads at a range of 0 to 3 weight percent. Pelletcompounding was completed on a 19 mm co-rotating twin screw extruderusing our 3 hole die plate. Our feed rates were controlled sufficientlyto get close to our targeted volumetric levels. Puck densitycalculations were used to confirm the ratio of the 0.6× specific gravityglass beads to the 1.9 specific gravity THV polymer and to backcalculate the ratio of glass bead to polymer in the generated samples.Furthermore, we added the glass beads to the throat of the machine alongwith the polymer powder. As is commonly done, it would be beneficial toadd the glass to molten polymer to reduce shear damage to the hollowspheres. The formulations were sensitive to residence time in the 19 mmcompounder. The material would burn up almost immediately if it was notconstantly moving through the machine. Extrusion was then completedusing a 1 inch single screw extruder with the 19 mm×3 mm die profile.Temperatures settings were the same as typically used for compoundingand extrusion of THV220A based formulations (185° C. flat temperatureprofile for compounding and Barrel-1=180° C., Barrel-2=150° C.,Barrel-3=150° C., Die=150° C. for profile extrusion). Processing noteswere taken throughout. ASTM Type-IV dog-bones were cut from the extrudedstrips and then tensile tested. The strain was normalized using a 1″gauge length. The following data in table 1 captures the resultsobtained with the glass sphere/THV composite materials.

TABLE 2 Example b c D e f THV-220, gms 50.0 55.0 55.0 55.00 55 3M iM30K50.0 44.5 44.0 43.50 44 Glass Beads, gms Additive, gms 0.0 0.5 1.0 1.51.0 Additive on IM30K, 0.0 1.0 2.0 3.0 2.0 % Density of IM30K, 0.60 0.620.62 gm/cc Puck Density 1.33 1.28 1.28 1.11 Extruded, gm/cc PredictedVol % 47 49 49 65 iM30k using a Density of 0.65 gm/cc for It PredictedWgt % 23 25 25 39 iM30k using a Density of 0.65 gm/cc for It Tensile atYield, Could 6.1 5.1 4.7 5 Mpa Elongation at not 9.8 7.9 7.6 3 Yield, %Tensile at Break, extrude 6.1 4.8 4.3 2.5 Mpa Elongation at 25 750 (825)590 (775) 20 (225) Break, %In sample 3f, two passes were used to attain the desired glass beadpacking level. This approach worked the best to get to the desiredpacking levels though potential damage to the glass is a concern.Samples 3d, 3e, and 3f were also tensile tested at a later date(approximately two months after being made) without negative changes tothe elongation at break, see parenthesis in the above table).

At a volume packing of about 50% glass, a 2% loading of NZ-12 on theiM30k on the glass resulted in a composite with a high percentage strainto failure. Interestingly, the strain to failure of the highly loadedcomposite (sample 3f at approximately 65 volume % glass beads) exceededthat of a composite sample loaded to 47% glass treated with 1% modifier(sample 3c). See FIG. 3. The data indicate that the effect of theinterfacial modifier is to increase the elasticity and compatibility ofthe glass and polymer. The aforementioned experiments reveal that theinterfacial modifier alters the interfacial strength of the hollow glassspheres and the fluorocarbon polymer. A loading of 2% is needed at avolumetric packing level of about 50% to maintain favorable properties.See, FIG. 5. The results indicate that packing levels greater that 50%may be attained, but will require higher modifier loading levels toperform.

Hollow Glass Bubbles in Tire Sidewall Compounds

The standard tire sidewall rubber compound used in these experimentswere prepared by and obtained from Continental Carbon Company ofHouston, Tex. The hollow glass bubbles, iM30k, were obtained from 3M.The tire sidewall compound was first banded on a two roll mill and thenthe indicated amount of iM30k, either uncoated or coated, was added andmixed in to form the final compound. The coated iM30k was easiest to mixin the compound compared to the uncoated iM30k. The resulting compoundswere evaluated for cure and physical properties according to the ASTMmethods below with the results shown in below.

Cure rheology: Tests were run on uncured, compounded samples using anAlpha Technologies Moving Die Rheometer (MDR) Model 2000 in accordancewith ASTM D5289-93a at 160 C, no preheat, 12 minutes elapsed time, and a0.5 degree arc. Both the minimum torque (M(L)) and highest torqueattained during a specified period of time when no plateau or maximumtorque was obtained (M(H)) were measured. Also measured were the timefor the torque to increase 2 units above M(L) (“t(s)2”), the time forthe torque to reach a value equal to M(L)+0.5(M(H)−M(L)) (“t′50”), andthe time for the torque to reach M(L)+0.9(M(H)−M(L)) (“t′90”).Press-Cure: Sample sheets measuring 150×150×2.0 mm were prepared forphysical property determination by pressing at about 6.9 mega Pascal(MPa) for 10 minutes at 160 C, unless otherwise noted.Physical properties: Tensile Strength at Break, Elongation at Break, andModulus at various elongations were determined using ASTM D412-92 onsamples cut from press-cured sheet with ASTM Die D. Units are reportedin MPa.Hardness: Samples were measured using ASTM D2240-85 Method A with a TypeA(2) Shore Durometer. Units are reported in points on the Shore-A scale.Tear Strength: Tear strength was determined using ASTM D624-00 onsamples cut from the press-cured sheet with ASTM Die C. The units arereported in kN/m.

Tire Application

One aspect of the invention relates to a tire having a tire portionhaving a layer containing a composite formed by combining hollow glassmicrospheres, a rubber formulation and other conventional tirecompounding components. The tire portion typically comprises an internallayer of the tire structure. One important tire structure can compriseis a tire sidewall or a tire tread portion. We have found that thecombination of a hollow glass microsphere having a coating of aninterfacial modifier, a rubber formulation and conventional tirecompounding components can result in a tire with substantial structuralintegrity but with reduced weight. Enhanced fuel efficiency is oftenobtained from a variety of wheeled vehicles from physically lightertires. We have found that an improved tire can contain an improved tirecomposition in the tire bead, sidewall or tread portion comprising alayer or a zone or a component of the tire comprising a dispersion of ahollow glass microsphere having an interfacial modifier coating in atire rubber formulation. The interfacial modifier used in the improvedtire formulations of the invention improves the association of thehollow glass microsphere with the rubber compounding formulation. Thisclose association of a physical nature, that does not involve couplingor covalent binding, maximizes reduced weight while avoiding reducingthe desirable properties of the rubber formulation. We have found thatreactive or coupling agents that have the capability of forming covalentbonds with the rubber components and the hollow glass microspheres arenot desirable since they tend to substantially reduce viscoelasticproperties which in turn can reduce the utility lifetime and otherbeneficial aspects of the tire.

Conventional tire structures have a variety of materials in a number offorms. Tire tread is made of rubber compositions containing rubberreinforcing carbon black silica and other curative or structuralmaterials. The tread material is formed on a tire carcass comprisingflexible but similar rubber compositions in typically closely associatedmanufacturing techniques.

The tire of the invention is an assembly of numerous components that arebuilt up in manufacturing equipment and then cured in a press under heatand pressure to form the final tire structure. Heat facilitates apolymerization reaction that cross-links rubber formulation into auseful rubber composition. The cured or volcanic polymers create anelastic quality that permits the tire to be compressed in an area ofroad contact but permit spring back to an original shape at low and highspeeds. Tires are made of a number of individual components that areassembled into the final structure. The tire inner liner is an extrudedrubber sheet compounded with additives at every level results in low airpermeability. This inner liner ensures that the rubber tire willmaintain high pressure air for extended use periods. The tire body plyis a calendar to sheet consisting of a layer of rubber a layer of fabrica second layer of rubber and other components that provide strength orrun-flat capabilities. Depending on speed and vehicle weight tires canhave from 2 to 5 or more ply layers. The tire sidewall is anon-reinforced rubber extruded profile. The sidewall formulationprovides abrasion resistance and environmental resistance. The sidewalldestabilizes to heat and oxidation. The tire structure includeshigh-strength steel wire encased in a rubber compound to providemechanical strength and stability to the tire structure. The apex andbead structure is a triangular extruded profile providing a cushionbetween the rigid bead and the flexible inner liner and body plyassembly of the tire. Tires typically comprise either a bias or radialply belt. Such belts typically comprise calendared sheets consisting ofrubber layers closely spaced steel cords and additional rubber layers.The belts give the tire strength and resistance while retainingflexibility. The tread is a thick extruded profile that surrounds thetire carcass. Tread compounds include additives to prove or impart wearresistance and traction in addition to resistance to heat and oxidation.Many tires include extruded components that can be formed between, forexample, the belt package and the tread to isolate the tread formechanical wear from steel belts. Such technology can improve thelifetime of the tire by isolating internal tire structures. Tirecomponents are typically made from natural or synthetic rubbersincluding polyisoprene or other conventional elastomer materials. Theelastomers include styrene butadiene copolymers polybutadiene polymershalo-butyl rubbers and others. Tire formulations also comprise carbonblack for reinforcement and abrasion characteristics, silica, sulfurcross-linking compounds, vulcanization accelerators activators etc,antioxidants, anti-ozone compounds and textile and steel fabric andfibers.

Tire plant processing is traditionally divided into compounding,component preparation, building and curing.

Compounding is the operation of bringing together all the ingredientsrequired to mix a batch of rubber compound. Each component has adifferent mix of ingredients according to the properties required forthat component. Mixing is the process of applying mechanical work to theingredients in order to blend them into a homogeneous substance.Internal mixers are often equipped with two counter-rotating rotors in alarge housing that shear the rubber charge along with the additives. Themixing is done in three or four stages to incorporate the ingredients inthe desired order. The shearing action generates considerable heat, soboth rotors and housing are water-cooled to maintain a temperature lowenough to assure that vulcanization does not begin.

After mixing the rubber charge is dropped into a chute and fed by anextruding screw into a roller die. Alternatively, the batch can bedropped onto an open rubber mill batchoff system. A mill consists oftwin counter-rotating rolls, one serrated, that provide additionalmechanical working to the rubber and produce a thick rubber sheet. Thesheet is pulled off the rollers in the form of a strip. The strip iscooled, dusted with talc, and laid down into a pallet bin. The idealcompound at this point would have a highly uniform material dispersion;however in practice there is considerable non-uniformity to thedispersion. This is due to several causes, including hot and cold spotsin the mixer housing and rotors, excessive rotor clearance, rotor wear,and poorly circulating flow paths. As a result, there can be a littlemore carbon black here, and a little less there, along with a few clumpsof carbon black elsewhere, that are not well mixed with the rubber orthe additives.

In tire compounding processes, the down or rubber material is typicallyadded to a mixing apparatus, mixing is initiated and the powderedcomponents are blended into the rubber. We have found that incorporatinghollow glass spheres into the rubber alone or with conventional powderedcomponents is difficult. The low density and fine character of thehollow glass along with the difference in surface character between theglass and the rubber prevent the ready incorporation of powder hollowglass spheres into the rubber material. We have found that for uncoatedhollow glass spheres that the low density glass with or without otherpowdered components can be first added to a mixer, followed by the morerubber portion. This order of addition can result in successfulincorporation of materials into the rubber formulation. In the instancethat conventional compounding techniques are to be followed inmanufacturing tire formulations using hollow glass spheres, we havefound that conventional processes can be used, surprisingly, if thehollow glass spheres are pretreated with an effective amount of theinterface modifier. In such a process, effective amount of the interfacemodifier comprising is formed in a coating on the surface of the hollowglass spheres. This pre-coating step permits the ready incorporation ofglass particles into the rubber formulation alone or in combination withother powdered components.

Components fall into three classes based on manufacturingprocess—calendaring, extrusion, and bead building. The extruder machineconsists of a screw and barrel, screw drive, heaters, and a die. Theextruder applies two conditions to the compound: heat and pressure. Theextruder screw also provides for additional mixing of the compoundthrough the shearing action of the screw. The compound is pushed througha die, after which the extruded profile is vulcanized in a continuousoven, cooled to terminate the vulcanization process, and either rolledup on a spool or cut to length. Tire treads are often extruded with fourcomponents in a quadraplex extruder, one with four screws processingfour different compounds, usually a base compound, core compound, treadcompound, and wing compound. Extrusion is also used for sidewallprofiles and inner liners. The calender is a series of hard pressurerollers at the end of a process. Fabric calenders produce an upper andlower rubber sheet with a layer of fabric in between. Steel calenders doso with steel cords. Calenders are used to produce body plies and belts.A creel room is a facility that houses hundreds of fabric or wire spoolsthat are fed into the calender. Calenders utilize downstream equipmentfor shearing and splicing calendered components.

Tire building is the process of assembling all the components onto atire building drum. Tire-building machines (TBM) can be manuallyoperated or fully automatic. Typical TBM operations include thefirst-stage operation, where inner liner, body plies, and sidewalls arewrapped around the drum, the beads are placed, and the assembly turnedup over the bead. In the second stage operation the belt package andtread are applied and the green tire is inflated and shaped. Allcomponents require splicing. Inner liner and body plies are spliced witha square-ended overlap. Tread and sidewall are joined with a skivedsplice, where the joining ends are bevel-cut. Belts are spliced end toend with no overlap. Splices that are too heavy or non-symmetrical willgenerate defects in force variation, balance, or bulge parameters.Splices that are too light or open can lead to visual defects and insome cases tire failure. The final product of the TBM process is calleda green tire, where green refers to the uncured state.

Curing is the process of applying pressure to the green tire in a moldin order to give it its final shape, and applying heat energy tostimulate the chemical reaction between the rubber and other materials.In this process the green tire is automatically transferred onto thelower mold bead seat, a rubber bladder is inserted into the green tire,and the mold closes while the bladder inflates. As the mold closes andis locked, the bladder pressure increases so as to make the green tireflow into the mold, taking on the tread pattern and sidewall letteringengraved into the mold. The bladder is filled with a recirculating heattransfer medium, such as steam, hot water, or inert gas. Temperaturesare in the area of 350±40 degrees Fahrenheit with pressures around350±25 PSI for curing. Passenger tires cure in approximately 15 minutes.At the end of cure the pressure is bled down, the mold opened, and thetire stripped out of the mold. The tire may be placed on a PCI, orpost-cure inflator, that will hold the tire fully inflated while itcools. There are two generic curing press types, mechanical andhydraulic. Mechanical presses hold the mold closed via toggle linkages,while hydraulic presses use hydraulic oil as the prime mover for machinemotion, and lock the mold with a breech-lock mechanism.

In such a structure, the glass microsphere and rubber elastomercomposition of the invention can be used in a variety of the tirecomponents. Preferably the compositions of the invention are used as aninternal component for making the tire carcass, sidewall or under treadcomponent.

Conventional rubber tire formulations were prepared containing glassmicrosphere and made into tire sidewall structures. The interface allowsour coatings enable the smooth incorporation of the glass bubbles intothe tire formulation and obtained as to reduce weight withoutcompromising structural integrity. Our data is as follows:

Evaluation of Glass Bubbles in a Tire Sidewall Formulation Hollow GlassBubbles in Tire Sidewall Compounds

The standard tire sidewall rubber compound used in these experimentswere prepared by and obtained from Continental Carbon Company ofHouston, Tex. The hollow glass bubbles, iM30k, were obtained from 3M.The tire sidewall compound was first banded on a two roll mill and thenthe indicated amount of iM30k, either uncoated or coated, was added andmixed in to form the final compound. The coated iM30k was easiest to mixin the compound compared to the uncoated iM30k. The resulting compoundswere evaluated for cure and physical properties according to the ASTMmethods below with the results shown in Table 2.

Cure rheology: Tests were run on uncured, compounded samples using anAlpha Technologies Moving Die Rheometer (MDR) Model 2000 in accordancewith ASTM D5289-93a at 160 C, no preheat, 12 minutes elapsed time, and a0.5 degree arc. Both the minimum torque (M(L)) and highest torqueattained during a specified period of time when no plateau or maximumtorque was obtained (M(H)) were measured. Also measured were the timefor the torque to increase 2 units above M(L) (“t(s)2”), the time forthe torque to reach a value equal to M(L)+0.5(M(H)-M(L)) (“t′50”), andthe time for the torque to reach M(L)+0.9(M(H)−M(L)) (“t′90”).Press-Cure: Sample sheets measuring 150×150×2.0 mm were prepared forphysical property determination by pressing at about 6.9 mega Pascal(MPa) for 10 minutes at 160 C, unless otherwise noted.Physical properties: Tensile Strength at Break, Elongation at Break, andModulus at various elongations were determined using ASTM D412-92 onsamples cut from press-cured sheet with ASTM Die D. Units are reportedin MPa.Hardness: Samples were measured using ASTM D2240-85 Method A with a TypeA(2) Shore Durometer. Units are reported in points on the Shore-A scale.Tear Strength: Tear strength was determined using ASTM D624-00 onsamples cut from the press-cured sheet with ASTM Die C. The units arereported in kN/m.

Tire Application

One aspect of the invention relates to a tire having a tire portionhaving a layer containing a composite formed by combining hollow glassmicrospheres, a rubber formulation and other conventional tirecompounding components. The tire portion typically comprises an internallayer of the tire structure. One important tire structure can compriseis a tire sidewall or a tire tread portion. We have found that thecombination of a hollow glass microsphere having a coating of aninterfacial modifier, a rubber formulation and conventional tirecompounding components can result in a tire with substantial structuralintegrity but with reduced weight. Enhanced fuel efficiency is oftenobtained from a variety of wheeled vehicles from physically lightertires. We have found that an improved tire can contain a tire portion inthe tire bead, sidewall or tread portion comprising a layer or a zone ora component of the tire comprising a dispersion of a hollow glassmicrosphere having an interfacial modifier coating in a tire rubberformulation. The interfacial modifier used in the improved tireformulations of the invention improves the association of the hollowglass microsphere with the rubber compounding formulation. This closeassociation of a physical nature, that does not involve coupling orcovalent binding, maximizes the reduced weight while avoiding thedesirable properties of the rubber formulation. We have found thatreactive or coupling agents that have the capability of forming covalentbonds with the rubber components and the hollow glass microspheres arenot desirable since they tend to substantially reduce viscoelasticproperties, which in turn can reduce the utility lifetime and otherbeneficial aspects of the tire.

Tire plant processing is traditionally divided into compounding,component preparation, building and curing. In tire compoundingprocesses, the rubber material is typically added to a mixing apparatus,mixing is initiated and the powdered components are blended into therubber. We have found that incorporating hollow glass spheres into therubber alone or with conventional powdered components is difficult. Thelow density and fine character of the hollow glass along with thedifference in surface character between the glass and the rubber preventthe ready incorporation of powder hollow glass spheres into the rubbermaterial. We have found that for uncoated hollow glass spheres that thelow density glass with or without other powdered components can be firstadded to a mixer, followed by the more rubber portion. This order ofaddition can result in successful incorporation of materials into therubber formulation. In the instance that conventional compoundingtechniques are to be followed in manufacturing tire formulations, usinghollow glass spheres, we have found that conventional processes can beused, surprisingly, if the hollow glass spheres are pretreated with aneffective amount of the interface modifier. In such a process, effectiveamount of the interface modifier comprising about 0.005 to 8.0 weightpercent of the interfacial modifier is formed in a coating on thesurface of the hollow glass spheres. This pre-coating step permits theready incorporation of our particles into the rubber formulation aloneor in combination with other powdered components.

In the tire building process, where the various components of tiremanufacturing and tire materials are brought together, the glassmicrosphere and rubber elastomer composition of the invention can beused in a variety of the tire components. Preferably the compositions ofthe invention are used as an internal component for making the tirecarcass, sidewall or under tread component.

Conventional rubber tire formulations were prepared containing glassmicrosphere and made into tire sidewall structures. The interface allowsour coatings enable the smooth incorporation of the glass bubbles intothe tire formulation and obtained as to reduce weight withoutcompromising structural integrity.

Internal Mixing Study of the Tire Sidewall Compound Containing GlassBubbles Procedure and Test Methods

The standard tire sidewall rubber compound used in these experimentswere prepared by and obtained from Continental Carbon Company ofHouston, Tex. One compound contained 50 phr carbon black and the other 5phr. The hollow glass bubbles, iM30k, were obtained from 3M. The tiresidewall compound was first banded on a two roll mill and then theindicated amount of iM30k or 5000, either uncoated or coated, was addedand mixed in to form the final compound. The coated iM30k was easiest tomix in the compound compared to the uncoated iM30k. The resultingcompounds were evaluated for cure and physical properties according tothe ASTM methods below.

Cure rheology: Tests were run on uncured, compounded samples using anAlpha Technologies Moving Die Rheometer (MDR) Model 2000 in accordancewith ASTM D5289-93a at 160° C., no preheat, 12 minutes elapsed time, anda 0.5 degree arc. Both the minimum torque (M(L)) and highest torqueattained during a specified period of time when no plateau or maximumtorque was obtained (M(H)) were measured. Also measured were the timefor the torque to increase 2 units above M(L) (“t(s)2”), the time forthe torque to reach a value equal to M(L)+0.5(M(H)−M(L)) (“t′50”), andthe time for the torque to reach M(L)+0.9(M(H)−M(L)) (“t′90”).Mooney Scorch: Tests were run on uncured, compounded samples inaccordance with ASTM D1646-06.Press-Cure: Sample sheets measuring 150×150×2.0 mm were prepared forphysical property determination by pressing at about 6.9 mega Pascal(MPa) for 10 minutes at 160° C.Physical properties: Tensile Strength at Break, Elongation at Break, andModulus at various elongations were determined using ASTM D412-92 onsamples cut from press-cured sheet with ASTM Die D. Units are reportedin MPa.Hardness: Samples were measured using ASTM D2240-85 Method A with a TypeA(2) Shore Durometer. Units are reported in points on the Shore-A scale.Tear Strength: Tear strength was determined using ASTM D624-00 onsamples cut from the press-cured sheet with ASTM Die C. The units arereported in kN/m.

All of the tire sidewall compounds shown in Table 4 were mixed in astandard Farrel laboratory BR banbury. A conventional 2-pass mix wasemployed. The first pass (with all the ingredients except for theaccelerator and sulfur) was discharged at 160° C., while the second pass(with the accelerator and sulfur) was discharged at 100° C. At first aconventional mix, which involves adding the polymer to the banbury andthen the dries, did not work when attempting to make the compoundcontaining 60 phr uncoated iM30K. The compound would not come together.An upside down mix, which involves adding the dries to the banbury firstand then the polymer, was then tried. Compounds containing 30 and 60 phrof uncoated and IM coated iM30K were mixed using this method. A compoundcontaining 60 phr of IM coated iM30K was also mixed the conventional wayand was successful.

Standard Tire Sidewall Formulations Containing Glass Spheres

TABLE 3 Compound # 1 (a) 2 (b) 3 (b) 4 (b) 5 (b) 6 (a) 7 (c) Ingredient,phr SVR-3L 50 50 50 50 50 50 50 Taktene 1203 50 50 50 50 50 50 50 N 33050 50 50 50 50 50 50 iM30K 30 60 iM30K + 5.4 phr 32 63.2 63.2 63.2 KR 9SCalsol 510 10 10 10 10 10 10 10 Stearic Acid 2 2 2 2 2 2 2 Sunolite 2401 1 1 1 1 1 1 Santoflex 13 4 4 4 4 4 4 4 Wingstay 100 1 1 1 1 1 1 1 ZincOxide 3 3 3 3 3 3 3 TBBS 1 1 1 1 1 1 1 Sulfur 1.8 1.8 1.8 1.8 1.8 1.81.8 Formula Weight 173.8 203.8 205.8 233.8 237 237 237 Mix Time (1st3:22 2:10 2:15 3:10 2:00 2:40 NA Pass), mm, ss Power (1st Pass), 0.4100.296 0.338 0.305 0.258 0.267 NA KWH MDR @ 160° C., 0.5° Arc, 100 cpm,for 12 minutes ML, in-lb 1.81 2.78 3.00 3.81 4.38 4.54 1.74 MH, in-lb13.37 18.13 18.63 20.68 22.53 22.97 15.83 ΔT, in-lb 11.56 15.35 15.6316.87 18.15 18.43 14.09 ts2, minutes 2.94 1.95 2.19 1.72 1.97 2.00 2.60t′50, minutes 3.59 2.43 2.84 2.16 2.66 2.78 3.54 t′90, minutes 5.40 3.324.48 2.74 4.24 4.48 5.72 Mooney Scorch MS 1 + 30 @121° C. InitialViscosity, 23.3 56.7 51.1 56.6 61.7 61.7 30.7 MU Minimum 14.8 27.9 28.030.9 37.5 39.6 19.0 Viscosity, MU t3, minutes 30.2 20.8 23.1 18.5 20.120.3 30.1 t10, minutes 23.0 25.6 21.0 22.6 23.0 t18, minutes 24.0 26.822.0 23.8 24.2 Physical Properties after Press Cure for 12 minutes @160° C., Die D Tensile, psi 3080 1662 1745 1098 1092 1017 763 50%Modulus, 160 175 203 196 223 186 160 psi 100% Modulus, 260 220 242 208237 197 165 psi 200% Modulus, UN 408 460 339 371 310 250 psi Elongation,% 510 458 455 405 422 460 425 Shore A2 54 59 61 66 69 71 64 Hardness DieC Tear, lbf/in 320 133 147 100 119 111 101 Density, g/cc 1.099 1.0071.003 0.934 0.953 0.927 0.962 Density — 8.4 8.7 15.0 13.3 15.7 12.5Reduction, % Theo Density (% 0.984 (12) 0.983 (11) 0.915 (10.6) 0.915(16.4) 0.915 (6.6) 0.915 (16.6) Breakage) (a) Conventional (b) upsidedown mix. (c) iM30K + 6phr KR9S added to AW1 on open mill Mix

Modified glass bubbles incorporated easier into the compounds than theuncoated glass bubbles as determined by time and power to mix (compare1a to the other compounds). In addition to benefits in time and power,only interfacially modified glass bubbles could be incorporated into thetire formulations using a conventional mixing method; when unmodified,the glass bubbles had to be mixed via an upside down method. Asexpected, using an upside down method increased glass breakage. Lastly,adding the glass bubbles with the other ingredients improves thephysical properties.

Glass Beads and Hollow Sphere Study

Solid glass beads were acquired. Bead sizes were selected based uponpacking theory of solid spherical particles. Ultimate packing behaviorof hollow glass spheres is limited by the narrow size distribution ofthe hollow glass spheres. The beads were interfacially modified and usedas a proxy for hollow glass bubbles due to the wider size availabilityof beads to that of bubbles. In order show increased packing level, twosized solid glass beads were purchased and used to determine powderpacking behavior. The results are shown in Table 5 below.

TABLE 5 Amount Amount of Packing of Coating Density Bubble Bead G/ccSize μ Each Size Coating (%) (g/cc) Packing % 5000 2.43 11 100 none 01.573 63 5000 2.4 11 100 IM3 1.8 1.806 75 2429 2.43 85 100 none 0 1.48059 2429/5000 2.43 85/11 75/25 none 0 1.866 75 2429/5000 2.43 85/11 75/25IM1 2 1.982 83 2429/5000 2.40 85/11 75/25 IM3 1.8 1.951 80 iM30K 0.60 16100 none 0 0.374 62 iM30K 0.615 16 100 IM3 5.4 0.422 69 iM30K 0.605 16100 IM3 1.8 0.416 69 iM30K 0.608 16 100 IM4 3 0.406 67 iM30K 0.615 16100 IM5 5.4 0.426 69 iM30K 0.613 16 100 IM6 4.8 0.431 70

It is clear that the use of the different size glass particles increasespacking density. The findings here can be used to increase ultimateglass bubble loading in a continuous phase if different sized hollowglass bubble sizes were made and blended. Further hollow glass bubbleloading levels will be attainable that can reduce sidewall specificgravity to levels less than what has been done at this time. Also notethe increased packing density of interfacially modified hollow glassspheres over that of unmodified glass bubbles.

Thermal Conductivity within a Thermoplastic

Thermal conductivity testing of hollow glass bubble filled nylon vs.unfilled nylon was conducted. Samples consisted of 50 volume % 3M K1hollow glass spheres in a H.B. Fuller Co. nylon (polyamide) blend.

Testing was completed on using a Mathis TC-30 thermal conductometerwhich uses a modified hot wire technique. The unfilled resin samplemeasured at 0.23+1-0.01 W-K⁻¹ m⁻¹. The microsphere-filled samplemeasured at 0.11+/−0.01 W-K⁻¹ m⁻¹. The reduction, from the use of hollowglass spheres in the polymer composite, in thermal conductivity was 52%.Delrin was used as the reference material for a control. The referencewas measured at its accepted thermal conductivity value of 0.38 W-K⁻¹m⁻¹.

Rheological Benefits of Using Spherical Particles with IrregularlyShaped Particles

Additionally, using spherical particles enhanced rheological propertiesin the composite. Rough particles (TDI tungsten) and smooth particles(Ervin Industries S70 carbon steel) were interfacially modified. Theparticles were incorporated into a Dyneon PVDF 11008 polymer using threeratios of spherical to rough particles within a 19 mm B&P twin screwcompounder. The ratios were (1) all rough; (2) 50/50 volume % spherical:rough or (3) all spherical. For each particle ratio, the volumetricparticulate loading level within the polymer phase was systematicallyincreased until over-torque occurred. Melt temperature, torque, andpressure were recorded.

The presence of spherical particles enhanced rheological propertiesshown in FIG. 5. When comparing rough and the 50/50 blended particles,the spherical particles lowered melt temperature at a given particleloading and also allowed for higher overall particle loadings beforeover-torque occurred. While compounding entirely spherical particles,the compounder continued to run at all particulate loading levels,without over torque, at all volumetric loading levels evaluated. Theenhanced rheological properties of the 50/50 blended particles over thatof the spherical particles at loading levels above that where the roughparticles over-torqued the machine was unexpected.

The composites of the invention can be used in a number of applicationsthat use either the properties of the particulate in the composite orthe overall viscoelastic properties of the composite. The viscoelasticmaterials can be formed into objects using conventional thermoplasticpolymer forming techniques including extrusion, injection molding,compression molding, and others. The composites of the invention can beused in many specific applications such as in transportation (includingautomotive and aerospace applications), abrasive applications used toeither remove materials such as paint or corrosion or dirt or stains,uses where high density (6 to 17 g-cm⁻³) or low density (0.2 to 2g-cm⁻³) is useful, hunting and fishing applications or in mountingapplications where a base or mounting weight is needed. Specificapplications include fishing lure and jig, abrasive pads with aluminumoxide, silica or garnet used like sand paper or sanding blocks, abrasivepads with cleaning materials used like Scotchbright® pads for cleaningsurfaces, brake pads (aluminum oxide or garnet), apex seals for Wankel®or rotary engines, fuel applications (line, tank or seal), engine ordrive train counterweight, automotive or truck wheel weight.

An inorganic hollow glass sphere, ceramic, nonmetal or mineral particlepolymer composite can be made comprising the hollow glass and ceramic,inorganic, nonmetal or mineral particle, the majority of the particleshaving a particle size greater than about 5 microns. We believe aninterfacial modifier (IM) is an organic material that provides anexterior coating on the particulate promoting the close association (butwith substantially no covalent bonding to the polymer or particle) ofpolymer and particulate. Minimal amounts of the modifier can be usedincluding about 0.005 to 8 wt.-%, or about 0.02 to 3 wt. %. Such an IMcoating can have a thickness of about 0.10 to 1 microns.

The density of the composite can be about 0.2 to 5 gm-cm⁻³, 0.2 to 2gm-cm⁻³, 0.2 to 0.8 gm-cm⁻³. The composite can comprise a polymer phaseand a particle coating comprising an interfacial modifier. The compositehas a tensile strength of about 0.1 to 15 times, about 0.1 to 5 times,about 0.2 to 10 times, about 0.3 to 10 times that of the base polymerand a tensile elongation of about 5% and 100% of base polymer and cancomprise an inorganic nonmetal particle, the majority of the particleshaving a particle size of about 5 to 1000 microns in a polymer such as athermoplastic including a polyolefin (and a HDPE), a PVC, orfluoropolymer phase. The composite can have a tensile strength ofgreater than about 2 MPa with a particle morphology of the particulateof 1 to 10⁶ and the circularity of the particulate is 12.5 to 25 or 13to 20. Alternatively, the composite has a tensile strength of greaterthan about 2 MPa and the non-metal, inorganic or mineral particlecomprises a particle morphology of the particulate of 1 to 10⁶ and acircularity of 13 to 20. The composite has a tensile strength of about0.1 to 10 times that of the base polymer and a tensile elongation ofabout 10% and 100% of base polymer. The composite has a tensile strengthof about 0.1 to 5 time that of the base polymer and a tensile elongationof about 15% and 100% of base polymer. The particle comprises a mineralhaving a particle size (P_(s)) of about 15 to 1200 microns, a ceramichaving a particle size (P_(s)) of greater than about 10 microns, a solidglass sphere having a particle size (P_(s)) of about 15 to 250 microns,a silica sand or zirconium silicate having a particle size (P_(s)) ofabout 75 to 300 microns, an aluminum oxide, a garnet, or otherparticulate.

The polymer can comprise a fluoropolymer, a fluoro-elastomer, apolyamide, a nylon, a poly (ethylene-co-vinyl acetate), a syntheticrubber, a polyvinyl chloride, a polyolefin (including a high densitypolyolefin) such as a polyethylene (including a HDPE) a polypropylene orother such polymers or mixtures. The particles can have a coating ofabout 0.01 to 3 wt % of an interfacial modifier based on the composite.The particles have an excluded vol. of about 13 vol.-% to about 70vol.-%, or about 13 vol.-% to about 60 vol.-%.

The resulting composite has a thermoplastic shear of at least 5 sec⁻¹, adensity is less than 0.9 gm-cm⁻³, a density is about 0.2 to 1.4 gm-cm⁻³.

In preferred tire formulations the composite comprises a syntheticrubber polymer. The particle comprises a mixture of particles derivedfrom two distinct nonmetallic particulate compositions.

The particle comprises a mixture of at least one nonmetallic particulatecomposition and at least one metallic particulate composition. Thecomposite particle can comprise a coating of about 0.005 to 8 wt % of aninterfacial modifier, based on the composite.

The component can comprise a fishing lure or jig, an abrasive pad, thatcan be made comprising cleaning materials, a brake pad, a fuel componentcomprising a line a tank or seal, a drive train counterweight, anautomotive, truck, wheel weight.

The composites materials of the invention can comprise a hollow glassmicrosphere and polymer composite that includes about 30 to 87 volumepercent of a hollow glass microsphere having a particle size greaterthan about 5μ and having a coating of about 0.005 to 5 weight percent ofinterfacial modifier. The composite also includes a polymer phase, thepolymer can have a density of greater than 17 gm-cm⁻³. The composite canhave a composite density that is about 0.4 to 5 gm-cm⁻³ about 0.4 to 2gm-cm⁻³ or about 0.4 to 0.8 gm-cm⁻³. The composite can have a tensilestrength of about 2 to 30 times that of the base polymer, a tensileelongation of about 5% to 100% of the base polymer or about 20% to 100%of the base polymer. Further the composite can have a tensile strengthof about 10 to 20 times that of the base polymer in a tensile elongationof about 15% to 90% of the base polymer. When extruded, the compositehas a thermoplastic shear of at least about 5 or 15 sec⁻¹ and can have atensile strength of at least about 0.2 or 1.0 Mpa. Additionally thecomposite can comprise a packing extent that is greater than about 30volume percent or about 50 volume percent of the composite. The hollowglass microsphere in the composite has a particle size distribution thatincludes particles having a particle size P_(s) between about 10 to 1000microns, alternately about 10 to 300μ and more specifically about 10 to200. The composite the invention, in combination with a hollow glassmicrosphere can have a second particulate having a particle size thatdiffers from the microsphere by at least 5μ. Similarly the composite canhave a hollow glass microsphere and a second particle such that theparticle size is defined by the formula P_(S)≧2 P_(S) ¹ or P_(S)≦0.05P_(S) ¹ wherein P_(S) is the particle size of the hollow glassmicrosphere and P_(S) ¹ is the particle size of the particulate. Thecomposite particulate, apart from the hollow glass microsphere cancomprise virtually any other particle having a particle size that rangesfrom about 10 to about 1000μ. Such particles can include a metallicparticulate a solid glass sphere a second hollow glass microsphere, andinorganic mineral, a ceramic particle or mixtures thereof. While hollowglass spheres have a circularity of less than 15 indicating asubstantially circular particle, other particulate materials of theinvention using the composite can have a circularity showing a rough oramorphous particle character with a circularity greater than 12.5.Polymers used in the compositions of the invention include a variety ofthermoplastic materials including a polyamide, such as a nylon,poly(ethylene-co-vinyl acetate), a natural or synthetic rubber,polyvinyl chloride, a fluoro-polymer, or fluoroelastomer. The compositecan have a particle with greater than 5 vol-% of a particle having aparticle size P_(S) distribution ranging from about 10 to about 200microns and greater than 10 vol-% of a particulate in the range of about5 to 1000 microns. The particles can be a mixture of particles ofdiffering nonmetallic composition. The composite comprises about 0.01 to4 wt % of an interfacial modifier. The composite additionally comprisesan organic or inorganic pigment or an organic fluorescent dye.

A hollow glass microsphere and polymer composite can comprise about 90to 30 volume-% of a hollow glass microsphere having a density greaterthan 0.10 gm-cm⁻³ and less than 5 gm-cm⁻³ and a particle size greaterthan 8 microns; and about 10 to 70 volume-% of a polymer phase;

wherein the microsphere has a coating comprising about 0.005 to 8 wt.-%of an interfacial modifier; and wherein the composite density is about0.4 to 15 gm-cm⁻³. The density can be about 0.4 to 5 gm-cm⁻³ about 0.4to 2 gm-cm⁻³ or about 0.4 to 0.8 gm-cm⁻³

A shaped article comprising the composite comprises about 87 to 50 vol-%of a hollow glass microsphere, and having a particle size distributionhaving at least 10 wt.-% of a particulate within about 10 to 100 micronsand at least 10 wt.-% of the polymer particulate within about 100 to 500microns and for certain uses can have a density of about 0.4 to 0.8gm-cm⁻³. Such uses include an insulating layer comprising the compositeof claim 1 wherein the thermal transfer rate of the composite layer isless than 50% of the thermal transfer rate of a conventional polymercomposite layer, a sealant layer that can be used in an insulated glassunit, an acoustically insulating layer having a reduced sound transferrate, a protective layer having improved impact resistance comprisingthe composite layer(s) that after impact rebounds a structural memberused in a structure assembled using a fastener, wherein the structuralmember has an improved fastener retention, a barrier layer, acting as abarrier to gas mass transfer, the barrier layer, wherein thepermeability of the layer to argon, nitrogen, or a mixed gas having amajor proportion of nitrogen is reduced by at least 50%.

The composite can be used in a tire composition or formulationcomprising a vulcanizable rubber about 30 to 87 vol % of a hollow glassmicrosphere having a coating of about 0.005 to 8 wt. % an interfacialmodifier. Such composition can be made with a process of compounding atire rubber formulation, the method comprising adding about 30 to 80 vol% of a hollow glass microsphere having a coating of about 0.005 to 8 wt.% of an interfacial modifier, to a tire formulations compounding mixercontaining a un-vulcanized rubber.

While the above specification shows an enabling disclosure of thecomposite technology of the invention, other embodiments of theinvention may be made without departing from the spirit and scope of theinvention. Accordingly, the invention is embodied in the claimshereinafter appended.

1-61. (canceled)
 62. A method of manufacturing a hollow glassmicrosphere and polymer composite from a mixture, said methodcomprising: (a) pre-treating a hollow glass microsphere with aneffective composite forming amount of an interfacial modifier coatingwherein the hollow glass microsphere has a particle size of at leastabout 5 microns; (b) combining a polymer phase with about 30 to 95volume % of a pre-treated interfacial modifier coated hollow glassmicrosphere, in an amount sufficient to substantially occupy excludedvolume of a hollow glass microsphere particle distribution in thecomposite; and (c) compounding the mixture to form the compositecomprising the pre-treated hollow glass microspheres within the polymerphase; wherein the hollow glass microsphere exhibits a circularitygreater than 13 and an aspect ratio less than 1:3; and wherein theinterfacial modifier coating allows for greater freedom of movementbetween the pre-treated hollow glass microsphere within the polymerphase compared to the same composite without the exterior coating on thehollow glass microsphere, when measured under the same conditions. 63.The method according to claim 63, wherein about 5 to 60 volume % of thehollow glass microsphere composite comprises the polymer phase.
 64. Themethod according to claim 63, wherein the composite comprises about0.005 to 8 wt.-% of the interfacial modifier.
 65. The method of claim 63wherein the polymer phase comprises a polyamide, a nylon, apoly(ethylene-co-vinyl acetate), a synthetic rubber, a polyvinylchloride, a fluoropolymer or fluoroelastomer, a polyolefin, a thermosetpolymer, or a high-density polyolefin.
 66. The method of claim 63,wherein the composite has a density of about 0.20 to 15 gm-cm⁻³.
 67. Themethod of claim 63 wherein the composite additionally comprises a solidparticulate or a fiber, the particulate having a particle size (P_(s))of about 5 to 1000 microns and the fiber having an aspect ratio ofgreater than
 10. 68. A method of manufacturing a hollow glassmicrosphere composite, said method comprising: (a) pre-treating a hollowglass microsphere with an effective composite forming amount of aninterfacial modifier coating wherein the hollow glass microsphere has aparticle size of at least about 5 microns; (b) compounding a polymerphase with about 30 to 95 volume % of a pre-treated interfacial modifiercoated hollow glass microsphere, in an amount sufficient tosubstantially occupy excluded volume of a hollow glass microsphereparticle distribution in a blend; and (c) extruding the blend to formthe hollow glass microsphere composite comprising the pretreated hollowglass microspheres within the polymer phase; and wherein the interfacialmodifier coating allows for a greater freedom of movement between thepre-treated hollow glass microspheres within the polymer phase comparedto the same composite without the exterior coating on the hollow glassmicrosphere, when measured under the same conditions.
 69. The methodaccording to claim 68, wherein about 5 to 60 volume % of the hollowglass microsphere composite comprises the polymer phase.
 70. The methodaccording to claim 68, wherein the composite comprises about 0.005 to 8wt.-% of the interfacial modifier.
 71. The method of claim 68 whereinthe polymer phase comprises a polyamide, poly(ethylene-co-vinylacetate), a synthetic rubber, a polyvinyl chloride, a fluoropolymer, apolyolefin, a thermoset polymer.
 72. The method of claim 68, wherein thecomposite has a density is about 0.20 to 15 gm-cm⁻³.
 73. The method ofclaim 68 wherein the composite additionally comprises a solidparticulate or a fiber, the particulate having a particle size (P_(s))of about 5 to 1000 microns and the fiber having an aspect ratio ofgreater than
 10. 74. A method of manufacturing a hollow glassmicrosphere composite, said method comprising: (a) pre-treating a hollowglass microsphere with an effective composite forming amount of aninterfacial modifier coating wherein the hollow glass microsphere has aparticle size of at least about 5 microns; (b) compounding a polymerphase with about 30 to 95 volume % of the pre-treated interfacialmodifier coated hollow glass microsphere, in an amount sufficient tosubstantially occupy excluded volume of a hollow glass microsphereparticle distribution in the composite; and (c) melt processing thecomposite to form the hollow glass microsphere composite comprising thepre-treated hollow glass microspheres within the polymer phase; whereinthe interfacial modifier coating allows for a greater freedom ofmovement between the pre-treated hollow glass microspheres within thepolymer phase compared to the same composite without the exteriorcoating on the hollow glass microspheres, when measured under the sameconditions.
 75. The method according to claim 74, wherein said method isa sequential method.
 76. The method of claim 74 wherein the meltprocessing comprises extruding the hollow glass microsphere composite.77. The method according to claim 74, wherein said melt processingcomprises injection molding the hollow glass microsphere composite. 78.The method according to claim 74, wherein said melt processing comprisescompression molding the hollow glass microsphere composite.
 79. Themethod according to claim 74, wherein the composite comprises about0.005 to 4 wt. % of the interfacial modifier.
 80. The method accordingto claim 74, wherein about 5 to 60 volume % of the hollow glassmicrosphere composite comprises the polymer phase.
 81. The methodaccording to claim 74, wherein the composite comprises about 0.005 to 8wt.-% of the interfacial modifier.
 82. The method of claim 74 whereinthe polymer phase comprises a polyamide, a poly (ethylene-co-vinylacetate), a synthetic rubber, a polyvinyl chloride, a fluoropolymer, apolyolefin or blends thereof.
 83. The method of claim 74, wherein thecomposite has a density is about 0.20 to 15 gm-cm⁻³.
 84. The method ofclaim 74 wherein the comprises additionally comprises a solidparticulate or a fiber, the particulate having a particle size (P_(s))of about 5 to 1000 microns and the fiber having an aspect ratio ofgreater than
 10. 85. A composite formulation comprising: greater thanabout 59 to 90 vol. % of a glass microsphere having a coating of about0.0005 to 8 wt. % an interfacial modifier; and a natural or syntheticrubber phase, wherein the coating on the glass microsphere allows forgreater freedom of movement of the glass within the rubber phase, andthe percentages are based on the composite formulation.
 86. Thecomposite formulation of claim 85 wherein the microsphere is a hollowglass microsphere.
 87. The composite formulation of claim 85 wherein thecomposite formulation has a density is about 0.2 to 5 gm-cm⁻³.
 88. Thecomposite formulation of claim 85 wherein the rubber phase has a densitygreater than 1.7 gm-cm⁻³.
 89. The composite formulation of claim 85wherein the composite formulation has a tensile strength of about 0.1 to10 times that of the rubber phase.
 90. The composite of claim 85 whereinthe composite formulation has a tensile strength of about 0.1 to 10times that of the rubber phase and a tensile elongation of about 15% to90% of the rubber phase.
 91. The composite of claim 85 wherein thecomposite formulation has a thermoplastic shear at least about 5 sec⁻¹.92. The composite formulation of claim 85 wherein the compositeformulation has a tensile strength of at least 0.2 MPa and athermoplastic shear of at least 5 sec⁻¹.
 93. The composite formulationof claim 85 wherein the composite formulation comprises a hollow glassmicrosphere, a majority of the microspheres having a particle size P_(S)of about 10 to 1000 microns.
 94. The composite formulation of claim 85wherein the hollow glass microsphere has a particle size P_(S) of about5 to 300 microns.
 95. The composite formulation of claim 106 wherein thehollow glass microsphere has a particle size P_(S) of about 15 to 250microns.